Paleoenvironments of the Upper Cretaceous Dinosaur Park Formation in Southern Alberta, Canada

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2010 Paleoenvironments of the Upper Cretaceous Dinosaur Park Formation in southern Alberta, Canada

Matson, Christopher Cody

Matson, C. C. (2010). Paleoenvironments of the Upper Cretaceous Dinosaur Park Formation in southern Alberta, Canada (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/18677 http://hdl.handle.net/1880/47721 master thesis

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Paleoenvironments of the Upper Cretaceous Dinosaur Park Formation in southern

Alberta, Canada

Christopher Cody Matson

A THESIS

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

DEGREE OF MASTER OF SCIENCE

DEPARTMENT OF GEOSCIENCE

CALGARY, ALBERTA

JANUARY, 2010

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ii Abstract

Paleoenvironments of the Upper Cretaceous Dinosaur Park Formation are investigated

using paleosols preserved in Dinosaur Provincial Park, southern Alberta, Canada. Seven

different types of paleosols (pedotypes) are recovered and represent various aspects of an

alluvial-coastal floodplain including well-drained distal dry floodplains, better-drained

and topographically higher proximal dry floodplains, and seasonal wetlands. The

stratigraphic distribution of these paleosols reveals three distinct paleolandscapes:

predominantly well-drained habitats low in the formation give way to diverse habitats

with numerous landscape positions, eventually becoming coal dominated, hydromorphic,

and less diverse due to the increasing proximity of the Bear Paw Sea. Pedofeatures

preserved within paleosols correspond to palynological, macrofloral, and

sedimentological studies suggesting Dinosaur Park Formation paleoenvironments

experienced warm-temperate to subhumid conditions with periods of significant

precipitation and seasonality during the Late Cretaceous. The humid south-eastern coast of the United States, the tropical wet lowlands of Colombia, and the seasonal wetland habitats of Bangladesh serve as respectable modern analogs for Dinosaur Provincial Park during the Late Cretaceous.

iii Acknowledgements

I would like to thank all the persons involved with the guidance and preparation of this thesis, especially to Dr. Ron Spencer, without whom this thesis would not have been completed. I am deeply indebted to Dean Sandy Murphree, Dr. David Eaton, Dr. Charles

Henderson, Dr. Jessica Theodor, and Robert Clegg whose guidance and council kept this thesis together. I am also deeply indebted to the many people who helped edit portions of this thesis including Dr. Ron Spencer, Dr. Andrew Leir, Dr. François Therrien, and Dr.

Darla Zelenitsky. I also wish to thank the support staff of the Department of Geoscience, especially Cathy Hubble, without whom I would still be downloading forms and scratching my head.

The field aspects of this thesis could not have been completed without the assistance of the Royal Tyrrell Museum of Palaeontology (RTMP) and especially Dr. Don Brinkman and Dr. François Therrien. I also need to thank the staff of the RTMP Field Station especially Philip Hofer, Andrew Hunt, and Donna Martin. For their tireless work in the field, I wish to thank Josh Pidkowa, Kohei Tanaka, Sofie Forsström, Lauren Andres,

Annie Quinney, and Dr. Brinkman’s 2008 RTMP field volunteers.

I also wish to thank the many persons who held me up and kept me going including Erik and Sara Katvala, Amanda McGee, Dr. Jessica Theodor, Keely Obert, Kirstin Brink, and of course my parents John and Kathy Matson.

iv Dedication

To my parents…

Ad astra per aspera.

v Table of Contents

Approval Page ...... ii Abstract ...... iii Acknowledgements ...... iv Table of Contents ...... vi List of Tables ...... viii List of Figures and Illustrations ...... ix

CHAPTER ONE: INTRODUCTION ...... 12 1.1 Introductory statement ...... 12 1.2 Thesis objectives ...... 17 1.3 Organization of this thesis ...... 17 1.4 Study Area ...... 18

CHAPTER TWO: GEOLOGIC SETTING ...... 21 2.1 Regional Stratigraphy ...... 21 2.2 Regional Geology ...... 24 2.2.1 Paleogeography ...... 24 2.2.2 Paleodrainage ...... 25 2.2.3 Previous Paleoclimatic Study of Campanian southern Alberta ...... 26 2.3 Previous Geologic Research in Dinosaur Provincial Park ...... 27 2.3.1 Sedimentology ...... 27 2.3.2 Paleontology ...... 28 2.3.2.1 Stratigraphic Distribution of Vertebrate Fossil Taxa in the Upper Belly River Group ...... 29

CHAPTER THREE: MATERIALS AND METHODS ...... 32 3.1 Stratigraphic sections and their measurement ...... 32 3.2 Field sampling and preliminary identification of pedotypes ...... 32 3.3 Thin section analysis and description ...... 37 3.4 Determination of clay mineralology ...... 37 3.5 Geochemical analysis ...... 38 3.6 Pedotypes ...... 40

CHAPTER FOUR: FEATURES OF DINOSAUR PARK FORMATION PALEOSOLS ...... 42 4.1 Colour of paleosols ...... 42 4.1.1 Groundwater and surface water gley ...... 42 4.2 Bioturbation ...... 43 4.3 Microstructure and Fabric of Groundmass ...... 44 4.4 Clay accumulations ...... 45 4.5 Slickensides ...... 48 4.6 Ferruginous pedofeatures ...... 48 4.7 Siderite ...... 49 4.8 Coal ...... 49

vi CHAPTER FIVE: DINOSAUR PARK FORMATION PEDOTYPES...... 53 5.1 Category 1 pedotype ...... 53 5.1.1 Interpretation ...... 60 5.2 Category 2 pedotype ...... 62 5.2.1 Interpretation ...... 63 5.3 Category 3 pedotype ...... 67 5.3.1 Interpretation ...... 68 5.4 Category 4 pedotype ...... 71 5.4.1 Interpretation ...... 72 5.5 Category 5 pedotype ...... 77 5.5.1 Interpretation ...... 81 5.6 Category 6 pedotype ...... 83 5.6.1 Interpretation ...... 87 5.7 Category 7 pedotype ...... 87 5.7.1 Interpretation ...... 93 5.8 Non-pedogenically modified deposits ...... 94 5.8.1 Category A deposits ...... 94 5.8.1.1 Interpretation ...... 94 5.8.2 Category B deposits ...... 94 5.8.2.1 Interpretation ...... 95 5.9 Location of paleosols within Dinosaur Park Formation ...... 95

CHAPTER SIX: PALEOENVIRONMENTAL RECONSTRUCTION OF THE DINOSAUR PARK FORMATION ...... 97 6.1 Lowermost Dinosaur Park Formation paleolandscape ...... 97 6.2 Middle Dinosaur Park Formation paleolandscape ...... 98 6.3 Upper Dinosaur Park Formation paleolandscape ...... 99

CHAPTER SEVEN: SUMMARY AND PROSPECTUS ...... 102

REFERENCES ...... 106

APPENDIX A: DINOSAUR PROVINCIAL PARK SECTIONS ...... 115

APPENDIX B: MOLECULAR WEATHERING RATIOS ...... CD-ROM

APPENDIX C: CLIMOFUNCTIONS ...... CD-ROM

vii List of Tables

Table 3-1. Descriptions of paleosol horizon nomenclature...... 35

Table 3-2. Descriptions of paleosol subordinate horizon nomenclature...... 35

Table 3-3. Developmental categories and descriptions of paleosols used in this thesis. .. 36

Table 3-4. Drainage descriptions and categories for paleosols used in this thesis...... 36

Table 5-1. Pedotypes and their pedofeatures...... 57

viii List of Figures and Illustrations

Figure 1.1. Location of Dinosaur Provincial Park within southern Alberta, Canada...... 14

Figure 1.2. North America during the Campanian (Late Cretaceous) ...... 15

Figure 2.1. Simplified schematic cross-section of the Upper Cretaceous Series ...... 22

Figure 2.2. Stratigraphy of the Belly River Group...... 23

Figure 2.3. Inferred “faunal zones” within the Dinosaur Park Formation ...... 31

Figure 3.1. Photograph of JEOL JXA-8200 Electron Microprobe...... 38

Figure 4.1. Photomicrograph of root traces within ...... 44

Figure 4.2a. Photomicrograph of sample BB30-15...... 46

Figure 4.2b. Same as Figure 4.2a but in polarized light...... 47

Figure 4.3a. Photomicrograph of root traces...... 47

Figure 4.3b. Same as Figure 4.1a but under polarized light...... 48

Figure 4.5a. Photomicrograph ferruginous external hypocoating ...... 50

Figure 4.4b. Photomicrograph of external ferruginous hypocoating ...... 51

Figure 4.5. Photograph of Bat Section ...... 52

Figure 5.1a. Measured sections of the Dinosaur Park Formation...... 54

Figure 5.1b. Stratigraphic profile of Category 1 paleosol...... 58

Figure 5.1c. Hand sample from Bss horizon of Category 1 pedotype ...... 59

Figure 5.1d. Photomicrograph of iron concretions within Category 1 pedotype ...... 59

Figure 5.1e. Photomicrograph of grainostriation in Category 1 pedotype...... 61

Figure 5.1f. Photomicrograph of porostriation in Category 1 pedotype ...... 61

Figure 5.2. Stratigraphic profile of Category 2 paleosol...... 65

Figure 5.2a. Hand sample of Bw horizon within Category 2 pedotype ...... 66

Figure 5.2b. Photomicrograph of Category 2 paleosol...... 66

Figure 5.3. Stratigraphic profile of Category 3 paleosol...... 69

ix Figure 5.3a. Hand sample from Bt horizon within Category 3 pedotype ...... 70

Figure 5.3b. Photomicrograph of Category 3 pedotype ...... 70

Figure 5.4. Stratigraphic profile of Category 4 paleosol...... 73

Figure 5.4a. Hand sample of Bt horizon within Category 4 pedotype ...... 74

Figure 5.4b. Hand sample of Bt horizon within Category 4 pedotype ...... 74

Figure 5.4c. Photomicrograph of Category 4 paleosol ...... 75

Figure 5.4d. Photomicrograph of iron accumulations (A) within Category 4 pedotype. . 75

Figure 5.4e. Photomicrograph of lower Bt horizon within Category 4 pedotype...... 76

Figure 5.4f. Photomicrograph upper Bw horizon within Category 4 pedotype...... 76

Figure 5.5. Stratigraphic profile of Category 5 paleosol...... 78

Figure 5.5a. Hand sample of Category 5 pedotype ...... 79

Figure 5.5b. Hand sample of Category 5 pedotype containing clay coatings ...... 79

Figure 5.5c. Photomicrograph of 2Btg horizon within Category 5 pedotype ...... 80

Figure 5.5d. Photomicrograph of 1Btg horizon within the Category 5 pedotype...... 80

Figure 5.5d. Photomicrograph of upper Ag horizon...... 81

Figure 5.6. Stratigraphic profile of Category 6 paleosol...... 84

Figure 5.6a. Hand sample from Bt horizon of Category 6 pedotype ...... 85

Figure 5.6b. Exposures of lowermost Dinosaur Park Formation ...... 85

Figure 5.6c. Photomicrograph of 1Bg horizon within the Category 6 pedotype ...... 86

Figure 5.6d. Photomicrograph of 2Bg horizon within Category 6 pedotype...... 86

Figure 5.7. Stratigraphic profile of Category 7 paleosol...... 89

Figure 5.7a. Hand sample of upper Bt horizon within the Category 7 pedotype...... 90

Figure 5.7b. Photomicrograph of Bt horizon within the Category 7 pedotype...... 91

Figure 5.7c. Photomicrograph of Bt horizon within the Category 7 pedotype ...... 91

Figure 5.7d. Photomicrograph of Bt horizon within the Category 7 pedotype...... 92

x Figure 6.1. Illustration of climofunctions, paleoenvironments, and faunal turnovers in stratigraphic context of the Dinosaur Park Formation...... 101

xi 12

Chapter One: Introduction

1.1 Introductory statement

The Upper Cretaceous strata exposed in Dinosaur Provincial Park (the Park hereafter), Alberta, Canada (Figure 1.1) contain one of the most taxonomically abundant and diverse fossil vertebrate faunas known from the Campanian. Paleontological investigations in the Park have produced important specimens for over a century and have revealed an amazingly diverse fossilized terrestrial ecosystem. The sediments that hosted this ecosystem were deposited on an extensive costal and alluvial plain as part of an eastward tapering wedge during a transgressive phase of the Western Interior Seaway

(Figure 1.2; Jerzykiewicz and Norris 1994). The gradient of this lower coastal plain was extremely shallow, producing very sinuous meandering river systems with muddy floodplains (Eberth and Hamblin 1993). This fluvial system is preserved as numerous sedimentary facies including single- to multistoried paleochannels, inclined bedded sandstone, and crevasse splays that contain trough-cross-stratified sandstones, inclined heterolithic strata (IHS), and muddy overbank deposits. These muddy overbank deposits underwent subaerial exposure and modification and are preserved today as ancient soils or paleosols.

Despite nearly one-hundred years of study and excavation of hundreds of partial and nearly complete skeletons from the Park, the environmental context of these discoveries remain largely unexplored. This is due largely to poor documentation of early fossil discoveries. Béland and Russell (1978) were the first to evaluate the spatial and stratigraphic distributions of articulated and associated dinosaur skeletons within the Park using museum records and data in Sternberg (1950), Russell (1970, 1977), and Dodson

(1971). Although Béland and Russell (1978) consider the Oldman and Dinosaur Park formations as a single terrestrial lithostratigraphic unit (the Oldman Formation; later revised by Eberth and Hamblin (1993) to include the Dinosaur Park Formation), their division is, to this day, thought to reflect distinct temporal and ecological changes (Currie and Russell 2005). Using the data available, Béland and Russell (1978) suggest that the distribution, composition, and taphonomy of vertebrate fauna imply that the paleoenvironment of the Park consists of a patchwork of small open and closed habitats.

In order to place Dinosaur Park Formation fossils into their ecological context, a digital map database was generated using highly-accurate differential GPS technology in

1999 (MacDonald et al. 2005). To date, over 250 lost excavation sites have been relocated using this system and placed into exact stratigraphic context within the Park

(Tanke 2005). This recent effort to increase in the stratigraphic resolution of fossil remains in the Park has exposed many new questions regarding the relationship between the Park’s biota and their habitats.

Figure 1.1. Location of Dinosaur Provincial Park within southern Alberta, Canada. Dashed line within figure to the right indicates boundary of Dinosaur Provincial Park. Numbered squares correspond to stratigraphic sections measured for this thesis. 1) Gravel pit section, 2) Risk section, 3) Bone bed 30 section, 4) Bat section, 5) Centrosaur section, 6) Iddesleigh section. 14

Figure 1.2. North America during the Campanian (Late Cretaceous) showing approximate extent of Western Interior Seaway. “DPP” marks the location Dinosaur Provincial Park within what is now Alberta (modified from Williams and Stelck (1975)).

Many recent paleontologic studies of Late Cretaceous strata in southern Alberta,

Montana, Utah, and Texas invoke a possible paleoenvironmental connection to explain

the observed patterns. Hypothesized paleoenvironmental changes and gradients during

the Campanian are thought to be responsible for the relative absence of associated and

articulated dinosaur skeletons in the Oldman Formation (Dodson 1971, Dodson et al.

2004, Eberth and Currie 2005, Ryan and Evans 2005b), for differences observed in

vertebrate microfossil assemblages (Eberth 1990), for transitional sequences of faunal

elements in the Dinosaur Park Formation (Ryan and Evans 2005a), and for

paleobiogeographical patterns (provinciality, endemism, etc.) observed in Late

Cretaceous dinosaur faunas in the western interior of North America (see Lehman 2001).

Although the paleoenvironmental context of these discoveries is clearly

significant, no investigation of the Dinosaur Park Formation has attempted to thoroughly

document paleoenvironments using paleosols. The morphology and chemistry of

paleosols are the products of biota, topography and climate during their period of

exposure (Jenny 1941, Morozova 1995, Retallack 2001a, Retallack 2001b). Therefore, paleosols can be used to deduce paleoclimate, paleolandscapes, and paleoecology (Besly and Fielding 1989, Bown and Kraus 1981, Driese and Foreman 1992, Retallack 1983,

Therrien and Fastovsky 2000).

The paleosols within the Dinosaur Park Formation represent an important and hitherto untapped repository of paleoenvironmental data. Documentation and analysis of

the paleoenvironments of the Dinosaur Park Formation is essential in order to give

further insight into taphonomical, paleobiogeographical, and evolutionary questions that

remain in one of the richest fossil localities in the world.

1.2 Thesis objectives

In order to deduce paleoenvironments during the deposition of the Dinosaur Park

Formation, detailed investigation of the paleosols is performed and include 1) identification of distinct paleosol types, 2) interpretation of the pedogenic processes that were active in these paleosols, 3) reconstruction of the paleoenvironments and paleolandscapes in which these soils developed, and 4) identification of paleolandscape changes in the Dinosaur Park Formation.

1.3 Organization of this thesis

Chapter 2 presents the geologic background of the Dinosaur Park Formation of southern Alberta, Canada. A discussion of southern Alberta paleoclimate during the

Campanian (Late Cretaceous) is included. These paleoclimate data are taken principally from palynological and paleobotanical studies but also include data from stable isotope and marine paleoclimate research. Lastly, a discussion of the stratigraphic distribution of fossil vertebrates is included.

Chapter 3 describes the materials and methods used to complete the research described in this thesis. Here, the field and laboratory analysis are described, including a description of how the pedotype method of Retallack (1994) was modified and incorporated into this study. Additionally, the use of paleosol horizon nomenclature is explicitly described to avoid shorthand confusion in the following text appendices.

Chapter 4 describes the results obtained from this investigation. Descriptions of the characteristic features of Dinosaur Park Formation paleosols using the terminology of

Bullock et al. (1985) are included. The implications of the various pedofeatures are also discussed.

Chapter 5 describes and interprets the seven pedotypes and two non-

pedogenically modified deposits documented in the Dinosaur Park Formation. Where

possible, the landscape position of each paleosol is estimated relative to active channels.

The paleoclimate, in terms of mean annual temperateure (MAT) and mean annual

precipitation (MAP), is presented.

Chapter 6 discusses the paleosols in terms of their paleolandscape implications.

Within the Dinosaur Park Formation, three distinct paleolandscapes are elucidated using

the type and stratigraphic distribution of the seven pedotypes. The relationship between

climate/environment and dinosaur faunas (including faunal turnovers) is briefly

discussed.

Finally, Chapter 7 summarizes the results, conclusions, and the prospectus of this

research including the relationship between ornithischian faunal turnovers.

1.4 Study Area

The seven stratigraphic sections measured for this thesis are all located within or

adjacent to the Park in southern Alberta, Canada. The Park is located in southern Alberta

and is approximately 180 km southeast of Calgary (Figure 1.1). The Park encompasses approximately 9,000 hectares with approximately 75 km2 of badlands outcrop developed

34 km west-to-east and 16 km north-to-south along the Red Deer River. The badlands

exposures of the Park include the upper 90 metres of the Belly River Group and therefore

expose the upper portion of the Oldman Formation and, in places, all of the Dinosaur

Park Formation (Currie 2005, Eberth 2005). The park was established in 1956 by the

Province of Alberta in recognition of its significant scientific importance and later

designated the first paleontological World Heritage Site in 1979 by the United Nation’s

Educational, Scientific and Cultural Organization (UNESCO) in 1979. The Park is administered by Alberta Recreation and Parks and is co-operated with staff from the

Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta. All of the stratigraphic sections measured for this thesis are south of the Red Deer River (Figure 1.1).

Paleosols

Paleosols are ancient soils (Retallack 1997b) and contain a variety of characteristic features that allow them to be easily recognized. These include fossil root traces, gradational layering, and distinctive three-dimensional features comparable to soil peds or cutans (Retallack 1988b). Paleosols commonly contain one or more of these ancient soil features (pedofeatures hereafter) some of which can be used to reconstruct the ancient environments that the paleosols developed under. This is because paleosols, and the pedofeatures they contain, are an in situ trace of a complete ancient ecosystem.

Reconstructions of terrestrial Phanerozoic (and Precambrian) landscapes are increasingly profited from paleopedology, the study of paleosols (e.g. Bronger et al.

1994, Driese et al. 2005, Fastovsky and McSweeney 1987, Kahmann and Driese 2008,

Kemp 1999, McCarthy 2002, McCarthy and Plint 1998, Sheldon et al. 2002). Typically, paleosols are used to correlate facies changes within rock strata because most paleosols usually represent a type of unconformity (see Bown and Kraus 1981, Kraus 1987, etc.).

In this manner, “pedofacies” are identified in ancient fluvial environments and described in terms of pedogenic maturity and sediment accumulation in order to infer the geomorphic processes active during the time of soil formation (pedogenesis). Although this technique can support the study of potential economically significant hydrocarbon deposits, the specific characteristics of the ancient environment remain elusive.

Using an alternative method, paleosols are described and given modern soil horizon nomenclature and taxonomy in order to more directly infer environmental and climatic factors (see Feakes and Retallack 1988, Retallack 1983, 1994, etc.) Due to the nature of modern soil taxonomy (see Section 3.2), this approach has been criticized as relying on the resemblance of modern soils to paleosols and application of the modern soil taxonomy in order to infer past environments and climates without knowledge of ancient climate conditions or weathering processes during the time of soil formation

(Dahms 1998, Dahms and Holliday 1998, Mack et al. 1993).

Although assigning paleosols to modern soil classifications can lead to misleading interpretations, pedofeatures within paleosols can still contain ancient environmental and climatic signals. By isolating pedogenic features that are indicative of climatic processes, such as the presence of pedogenic carbonate, evidence of clay translocation, colour, occurrence of coal, oxidation state of iron, and evidence of ped heave, inferences about prevailing paleoenvironment and paleoclimate can be made (Driese and Ober 2005,

Jenny 1941, Retallack 2001b).Techniques such as thin section micromorphology allow for the identification of soil features (such as clay coatings, concretions, etc.) relevant to paleoenvironmental interpretations (Bronger et al. 1994, Kemp 1999, Kraus 1999), whereas geochemical analyses provide proxies of pedogenic processes (Retallack 2001a) and can give estimates of paleoprecipitation (Sheldon et al. 2002). These analyses provide genetic, temporal, and spatial information on soil forming processes as influenced by environment of pedogenesis (Kraus and Hasiotis 2006, McCarthy and Plint

1998, Morozova 1995).

Chapter Two: Geologic setting

2.1 Regional Stratigraphy

The Upper Cretaceous series in western North America consists of a complex interfingering of western non-marine facies and eastern marine facies with a paralic facies between. The terrestrial component of this sediment is a wedge, deposited by an extensive (≥ 400 km; Eberth and Getty 2005) coastal and alluvial plain that progressively thins from a maximum thickness of 5800 m near the Rocky Mountain front, to less than

200 m at its erosional edge some 1600 km to the east (McLean 1971). The Belly River

Group represents middle to late Campanian terrestrial deposition of siliciclastic sediments during the “Bearpaw Cycle” of Kauffman and Caldwell (1994): a lowstand-highstand systems tract cycle of the Western Interior Seaway (Figure 2.1; Haq 1988, Jerzykiewicz and Norris 1994). The Dinosaur Park Formation is the uppermost unit of the Belly River

Group (Figure 2.2), deposited during the initial stages of this last major transgression of the Western Interior Seaway in southern Alberta (Eberth and Hamblin 1993,

Jerzykiewicz and Norris 1994). The Dinosaur Park Formation rests sharply and disconformably on the Oldman Formation (Figure 2.2) and consists of a lower sandy zone comprised predominantly of alluvial paleochannel facies and an upper muddy, overbank dominated succession capped by the Lethbridge Coal Zone and overlying marine

Bearpaw Formation (Eberth 2005, Eberth and Hamblin 1993). The upper Dinosaur Park

Formation-Bearpaw contact is identified as the uppermost contact of open marine shales on paralic siltstones (some carbonaceous) and sandstones (Eberth 2005).

Dinosaur Park Formation sandstones are muddy and texturally immature compared to the underlying Oldman Formation and are typified by very low quartz/chert

ratios, high plagioclase/k-spar ratios, and an abundance of volcanic rock fragments

(Eberth 2005). Paleochannels in the Dinosaur Park Formation are laterally extensive,

metre-to decametre thick, and single or multistoried. They contain clean sands with

trough-cross bedding, inclined heterolithic strata (IHS), carbonaceous drapes, and in situ

(authogenic) siderite (Eberth 2005). Both low and high sinuosity paleochannels co-occur

with some paleochannel widths estimated at over 200 metres (Eberth 2005).

Figure 2.1. Simplified schematic cross-section of the Upper Cretaceous Series in the western interior of Canada. Approximate location of Dinosaur Provincial Park strata given as gray box labeled “DPP.” (Modified from McLean (1971) and Wood (1985)).

Figure 2.2. Stratigraphy of the Belly River Group. All strata illustrated lie within the 33N Magnetochron. The stratigraphic extent of all exposures in Dinosaur Provincial Park are highlighted in gray. Abbreviations: c.z., Coal Zone; s.s., sandstone. Dates were produced using Potassium-Argon radiometric dating and are ± 0.96 Ma (Modified from Eberth (2005) and Eberth and Hamblin (1993)).

Paleocurrent data gleaned from paleochannel geometries indicate an east-southeast flow direction (Eberth 2005, Eberth and Hamblin 1993). Abundant heterolithic paleochannel deposits (rhythmites) throughout the Dinosaur Park Formation suggest paleochannel flow velocities varied (Eberth 2005). Eberth (2005) and Eberth and Getty (2005) suggest that the carbonaceous/sandy rhythmites and IHS in the Dinosaur Park Formation are products of autocyclic flow variation within the paleochannels and not tidally influenced ponding as has been previously suggested (see Koster and Currie 1987, Thomas et al. 1987, Wood

1989). The exact nature and degree of tidal influence and the presence of standing water

(outside of abandoned channel-fills) on the Dinosaur Park Formation landscape is not resolved using sedimentology alone.

Overbank facies within the Dinosaur Park Formation consist of laterally extensive, smectite clay rich, mudrock facies that are commonly host to paleosols.

Mudstone occurs as single (~ 2-6 m) or stacked units that approach 20 metres in thickness. Concretionary siderite horizons hosted in organic rich horizons within paleosols are abundant. Green to white bentonites (up to 50 cm thick) are also present in association with mudstone sequences (Eberth et al. 1992, Thomas et al. 1987). The

Lethbridge Coal Zone occupies the uppermost 15 metres of the Dinosaur Park Formation and contains U-shaped, mudstone-filled incised valleys (Eberth 1996) and no more than four sub-bituminous to lignite coal beds that are less than 1-metre thick (Jerzykiewicz and Norris 1994).

2.2 Regional Geology

2.2.1 Paleogeography

The geography of North America has significantly changed since the deposition of units exposed in the Park some 75 million years ago (see Figure 1.2). Due to continental drift, the present latitude of the Park at approximately 57° N is several degrees (6-8°) more northerly than during the Campanian (Eberth 2005, Marsaglia and

Klein 1983). The western interior of North America during the Late Cretaceous was mostly covered by a broad epeiric sea that reached from what is now the Gulf of Mexico to, at times, the Arctic Ocean (see Figure 1.2). The western margin of this sea, referred to as the Western Interior Seaway, experienced relatively rapid subsidence creating thick

25 successions of complexly interfingering marine and non-marine sediment (Jerzykiewicz and Norris 1994, Williams and Burk 1964). The western shoreline of the Sea migrated over time due to the relative sea-level fluctuations attributed to tectonic activity associated with the Laurentian orogenic belt to the west and variable rates of subsidence and clastic sediment input (McLean 1971, McLean and Jerzykiewicz 1978). Specifically, the four coarsening upward, transgressive-regressive megacycles in the Upper Cretaceous of the western interior represent distinct pulses of foreland molasse deposition that likely correspond to periods of orogenic activity in the still developing Cordillera (Weimer

1960). The deposition of the Belly River Group occurred during the uplift and deformation east of the Omineca Crystalline Belt during the initial development of the

Front Range Structures (Walker 1982) and concomitant to the third of these megacycles known as the “Bearpaw Cycle” of Kauffman and Caldwell (see Figure 2.1; 1994). The

Park was situated in the distal portion of a broad, low-lying alluvial plain that extended from the highlands in the west to the coast of the Western Interior Seaway in the east.

The deposition of the overlying Bearpaw Formation represents an abrupt reentrance of marine conditions due to subsidence within the basin and subsequent transgression of the

Western Interior Sea during the late Campanian.

2.2.2 Paleodrainage

During the Campanian of southern Alberta, the rising Cordillera in the west was drained by paleorivers that flowed toward the subsiding foreland basin in the east along a few distinct major valleys associated with structural re-entrants along the uplift boundary

(Eisbacher et al. 1974). Heavy mineral dispersal studies of Rahmani and Lerbekmo

(1975) suggest that these paleorivers flowed southeastwards across the coastal plain and

26 emptied into the Western Interior Seaway. Paleocurrent data obtained from the sediments of the Park also suggest that local paleodrainage was directed approximately southeastward (Dodson 1971, Eberth and Hamblin 1993, Koster 1983, Wood 1985).

2.2.3 Previous Paleoclimatic Study of Campanian southern Alberta

The paleoclimate of western North America during the Late Cretaceous has received intensive study. Oxygen and carbon isotope studies of the Bearpaw Sea ammonites indicate adjacent coastal water temperatures of 17-27° C (Forester et al.

1977). Mean annual precipitation in what is now the Park is estimated to have been 120 cm or more using tree fragments from Taxodiaceae (Béland and Russell 1978). The relative absence of desiccation features and footprints is used to suggest that discharge was perennial (Koster 1983). The presence of coal is also used to suggest that paralic conditions were abundant. Dodson (1971) and Béland and Russell (1978) suggest that the relative abundance of herbivorous dinosaur fauna in the Park would have required a rich flora to support and therefore, require prevailing humid conditions. The occurrence of growth rings in petrified wood, teeth, and vertebrae suggest the Park’s climate was subject to seasonality (Marsaglia and Klein 1983). Biotic and abiotic data suggest Park habitats were equable, frost-free, humid, and experienced moderate to high seasonal precipitation (Braman and Koppelhus 2005, Dodson 1971, Jarzen 1982, Koppelhus

2005b, Russell 1977).

2.3 Previous Geologic Research in Dinosaur Provincial Park

2.3.1 Sedimentology

The earliest detailed stratigraphic work on the exposures of the Belly River Group

was conducted by Dodson (1970, 1971) and Koster (1983). Although Dodson (1970,

1971) was primarily concerned with taphonomy, he concludes that the sediments of the

Park are fluviatile and contain both meandering and braided channel deposits. Koster

(1983) refined these earlier observations by recognizing three major lithofacies within the

upper Belly River Group: 1) cross-bedded sandstone, 2) fining-upward heterolithic

sequences, and 3) bentonitic mudstone. These facies are interpreted by Koster (1983) as

braided channel, meandering channel, and overbank deposits respectively. Wood (1985)

resolves four major lithofacies within the “Cathedral” area of the Park: trough cross- bedded sandstone, 2) large-scale inclined heterolithic strata (IHS), 3) large-scale inclined

bedding (IBS), and 4) massive shale facies. Wood (1985) regardes trough cross-bedded units as channel bottom and lower point bar deposits, IHS and inclined bedded strata

(IBS) sequences as products of complex lateral accretion macroforms that developed both upstream and downstream of a single point-bar or under varying discharge conditions.

However, Eberth (2005) suggests that a more thorough investigation of the Park’s coarse- grained facies suggests that IHS and IBS macroforms are established only after the initial development of straight, vertically aggrading channels. In this manner, the typically

depositional sequence in the Park begins with channel avulsion, and incision, deposition

of vertically aggraded sandstones that eventually give way to muddy, lateral-accretion

deposits and meandering channels.

Few studies focus specifically on the fine-grained facies of the Park. Numerous

authors note the presence of root traces, however, only a few describe these pedofeatures

in any detail. Eberth (2005) describes root traces within the Dinosaur Park Formation as

“varying in density and range from carbonaceous to clay replaced.” Wood (1985)

describes several pedofeatures within massive fine-grained facies from the Park including

“locally abundant rootlet traces,” vertical colour changes that are intermittently

discordant with bedding, and common slickensides (pgs. 51-53). Koster et al. (1987)

interpret the majority of the fine-grained units within the Dinosaur Park Formation as

deposits of poorly-drained, organic-rich paleoenvironments. The presence of the

Lethbridge Coal Zone within the upper 20 metres of the Dinosaur Park Formation clearly suggests that the approach of the Western Interior Seaway gave rise to waterlogged and swampy conditions. Moreover, five distinct marine flooding surfaces are detected using marine microfossils within the upper 30 metres of the Dinosaur Park Formation (Braman and Koppelhus 2005, Eberth 2005). These flooding surfaces can be laterally continuous with mud-filled incised valleys (Eberth 1996).

2.3.2 Paleontology

The sediments of the Park have yielded one of the most amazing fossilized terrestrial ecosystems ever discovered. In addition to the approximately 45 known dinosaur species, a myriad of other flora and fauna inhabited the Park during the

Campanian. Freshwater invertebrate remains are present but rare in the Park and consist primarily of bivalves and gastropods (Johnston and Hendy 2005). Freshwater vertebrate fossils include chondrichthyans (sharks, skates, and rays), Acipenseriformes (sturgeons and paddlefish), holostean-grade fishes (gar, bowfins, etc.), and teleosts (elopomorphs,

osteoglossomorphs, etc.). Amphibian fossils from the Park include frogs, salamanders,

and lissamphibians (Albanerpetonidae, Gardner 2005, Neuman and Brinkman 2005). The

remains of turtles, squamates (varanids, teiids, xenosaurids, and helodermatids),

crocodilians, plesiosaurs, pterosaurs, and choristoderes (Champsosaurus) are also present

(Brinkman 2005, Caldwell 2005, Gao and Brinkman 2005, Godfrey and Currie 2005,

Sato et al. 2005). Multituberculate, eutherian, and marsupial mammal fossils are principally known from isolated teeth found in the Park (Fox 2005). Over 500 palynomorph forms are also described from the Park and attest to the incredible floral diversity of southern Alberta during the Campanian (Braman and Koppelhus 2005).

2.3.2.1 Stratigraphic Distribution of Vertebrate Fossil Taxa in the Upper Belly River Group

Recent increases in the stratigraphic resolution of fossil material from the Park

elucidate more about the paleontology of vertebrate taxa than morphology alone. For

example, ornithischian fauna are now know to be unequally distributed throughout the

strata of the Dinosaur Park Formation (Currie and Russell 2005). Two possible faunal

shifts or “turnovers” within Ornithischia are suggested to exist within the Dinosaur Park

Formation (Figure 2.3; Evans and Ryan 2005, Ryan and Evans 2005b). The lowermost

Dinosaur Park Formation contains an abundance of vertebrate fossils. The vertebrate remains are preserved in a variety of taphonomic states from single, isolated bones to bone beds with little articulation, to fully articulated skeletons. In total, 13 of the 20 known ceratopsian bonebeds in the Dinosaur Park Formation occur within the lowermost

10 metres of the Formation and contain the remains of Centrosaurus apertus exclusively

(Eberth and Getty 2005). In hadrosaurs, Gryposaurus and Corythosaurus are confined to

30 the lower 30 metres of the Dinosaur Park Formation. Consequently, the lower 30 metres of the Dinosaur Park Formation comprise the “Centrosaurus-Corythosaurus” faunal zone

(Ryan and Evans 2005a).

The middle Dinosaur Park Formation contains the upper portion of the

“Centrosaurus-Corythosaurus” faunal zone and the entire “Styracosaurus-

Lambeosaurus” faunal zone (Ryan and Evans 2005a). Styracosaurus replaces

Centrosaurus within the Ceratopsidae approximately 30 metres above the base of the

Dinosaur Park Formation whereas Chasmosaurus russelli is confined to the lower 20 metres and Chasmosaurus belli is found 20-40 metres from the base. A similar pattern is observed in the hadrosaurs where Corythosaurus occurs in the lower two-thirds of the

Dinosaur Park Formation and is gradually replaced by Lambeosaurus lambei.

Prosaurolophus is also only found in the upper half of the Dinosaur Park Formation.

The uppermost sediments of the Dinosaur Park Formation include the Lethbridge

Coal Zone and contain the uppermost faunal zone composed of a “Pachyrhinosaurid” cetatopsian, the chasmosaurine Chasmosaurus irvinensis, and the lambeosaurine

Lambeosaurus magnicristatus. This final shift in the distribution of ornithischians is thought to reflect the increasing proximity to the Western Interior Seaway and paleoenvironmental shift from more alluvial environments to more paralic environments.

Figure 2.3. Inferred “faunal zones” within the Dinosaur Park Formation based on the stratigraphic distributions of ornithischian (ceratopsian and hadrosaurian) dinosaurs. (Modified from Dodson et al. (2004), Evans (2007), and Ryan and Evans (2005a)).

Chapter Three: Materials and methods

3.1 Stratigraphic sections and their measurement

During the summer of 2008, six stratigraphic sections in the Dinosaur Park and

Bearpaw formations were measured. Five of the sections are situated in the Natural

Preserve of Dinosaur Provincial Park (see Figure 1.1), and one section is located in the

eastern portion of the Park, 12 km north of Jenner, Alberta (Figure 1.1).

The sections were chosen because their near vertical exposures contained thick

mudstone intervals that maintain their position without slumping. A high-resolution GPS was used to geographically locate each section. The Oldman-Dinosaur Park and/or

Dinosaur Park-Bearpaw formational contacts are used as a datum to ascertain the

stratigraphic position of each section. Bed and horizon thicknesses within the various sections were measured using a Brunton compass, Jacob staff, and tape measure. Each facies encountered is described in terms of lithology, texture, sedimentary structure, and, where possible, degree of pedogenesis. Photographs are taken to document each section and any particular pedogenic features.

3.2 Field sampling and preliminary identification of pedotypes

Paleosols occur predominantly in mudstone and shale intervals (Boggs 2001) and are recognized by the presence of root traces, dispersed organic matter, or other conspicuous pedogenic features (sensu Retallack 1988a). Mudstone intervals encountered in each section are identified to be paleosols by excavating small hand samples and visually determining that they contain pedogenic features. Providing a given mudstone interval appeared to host a paleosol, a shoulder-width trench is excavated using a pick and shovel in order to produce a fresh surface for measurement and sampling. Indurated

33 channel sandstones encountered in the various sections are described from observations without significant trenching.

The following features of each mudstone interval are macroscopically described: boundary distinction, horizon thickness, Munsell colour, bioturbation, development of clay coatings, slickensides, nodules, dispersed organic matter, and root traces (Retallack

2001b). Horizons identified within paleosols are sampled at least once per horizon or at a

20-cm interval. The location of each sample is documented in field sketches of each section along with the other aforementioned descriptions to facilitate later analyses.

In order to more accurately describe paleosol matrix colour, the Munsell System, used by pedologists at the Soil Survey Staff of the United States Department of

Agriculture, is adopted for this study. After hand samples were collected in the field and dried, paleosol matrix colour were measured by visual comparison to Munsell colour chips. Munsell System colour is classified using three terms: hue, value, and chroma. Hue is divided into five principal values (red, yellow, green, blue, and purple) and five intermediate hues. These hues are represented numerically ranging from 0 (the boundary between purple and red) to 100. Each intermediate hue has a range of 10 units and is noted by using numbers such as 5YR or 7.5YR divided into red, yellow, green, blue, etc.

Value is determined numerically and ranges from 0 (absolute black) to 10 (absolute white). Chroma defines the degree of colour saturation from a gray of the same value.

Distinct paleosol horizons are difficult to identify (Kraus and Bown 1986,

Retallack 1983). Their occurrence in this study is inferred by the presence of intense bioturbation, inconspicuous illuvial features, geochemical differentiation, and relative position. Horizons that exhibit evidence of clay illuviation (such as clay coatings around

34 grains, pores, or root traces) and are clay enriched relative to underlying and overlying horizons are interpreted as Bt horizons (see Table 3.1). Bw horizons exhibit only minor traces of illuviation with poorly developed or absent clay coatings. Paleosol horizons with slickensides or strongly striated b-fabrics are classified as Bss horizons. Horizons with few paleosol features and a chroma of 1 on the Munsell Color Chart are considered gleyed (Bg or Cg) horizons. Horizons that underlie paleosols but lack extensive pedogenic modification are considered parent material or C-horizons. Conspicuous pedogenic features (abundance of organic matter, clay coatings, etc.) of distinct paleosol horizons are given appropriate subordinate descriptors in the field (see Table 3.2).

The development and relative drainage of the various pedotypes is inferred using qualitative properties such as thickness of diagnostic horizons and degree of mineral translocation (Tables 3.3 and 3.4 respectively; sensu Retallack 1988b). Discrimination of the various pedotypes is performed in the field based on conspicuous pedogenic features.

Field description is made more efficient by limiting sample collection and documentation to sections containing undescribed pedotypes.

Horizon Definition

O horizon Surface accumulation of organic material overlying a mineral soil

A horizon Accumulation of humified organic matter mixed with mineral fraction. Occurs at surface or below O horizon E horizon Underlies an O or A horizon and is characterized by less organic matter, less sesquioxides or less clay than the underlying horizon. Frequently light coloured because grains lack secondary coatings. Also known as an albic horizon. B horizon Underlies an O, A, or E horizon and shows discernable alteration of parent material. C horizon Subsurface horizon, excluding bedrock, with slightly more weathered material from which the soil formed or is presumed to have formed. Lacks properties of A and B horizons, but includes weathering as shown by mineral oxidation, accumulation or silica, carbonates, or more soluble salts, and gleying. R horizon Consolidated or weathered bedrock underlying the soil.

Table 3-1. Descriptions of paleosol horizon nomenclature. Modified from Retallack (1997a).

Subordinate symbols Description a Abundance of organic matter g Strong gleying ss Slickensides t Accumulation of clay Table 3-2. Descriptions of paleosol subordinate horizon nomenclature. Modified from Retallack (1997a).

Category Description of Development Very weakly- Root traces, no A horizon, little or very weak structural developed development, depositional fabric easily recognizable. Weakly-developed True A horizon with rooting (if present), subsurface horizons with evidence of clay translocation or gley. No true Bt horizon. May have vertic properties. Moderately-developed True A, OA, or O horizon with rooting, subsurface horizons with obvious evidence of clay translocation or gley. True Bt horizon. Well-developed Thick (60cm+) surficial organic (coal) horizon. May have especially thick(2-3m) subsurface (B) horizons. Obvious zones of eluviations and illuviation. Very well-developed Unusually thick (3m+) surficial organic (coal) horizon or subsurface (B) horizon(s). Obvious zones of eluviation and illuviation. Weathering of quartz. Table 3-3. Developmental categories and descriptions of paleosols used in this thesis. Modified from Retallack (1997a)

Drainage category Description of Drainage

Well drained A horizon, no gley colours, deeply penetrating (1m+) roots, argillans. Seasonally Drained A horizon (if present), penetrating roots, vertic properties including slickensides and surface cracks, developed Bt horizon. Wet with Dry History Organic surface horizon (A or OA), gley colours, deeply penetrating roots, developed Bt horizon. Poorly Drained Thick surface organic horizons (A or OA), gley colours, shallow rooting. Table 3-4. Drainage descriptions and categories for paleosols used in this thesis. Modified from Retallack (1997a).

3.3 Thin section analysis and description

One representative sample per paleosol horizon was sectioned by Calgary Rock and Materials Services to produce twenty-three thin sections. Each thin section is 30 µm thick, unstained, constituted using orosol epoxy, and affixed using Canada balsam with a cover slip. A transmitted-light petrographic microscope was used to examine each thin section.

The micromorphological and textural properties of each thin section are described using the terminology of Bullock et al. (1985) and reported in Appendix A. Relative abundances of the various mineral constituents for each thin section are estimated using

Shvetsov’s diagrams (Terry and Chilingar 1955). Lithological properties described include particle size, abundance, sorting, colour, shape, surface roughness/smoothness, boundary, variability, orientation and distribution (sensu Bullock et al. 1985). Pedogenic features described include type and degree of primary mineral weathering, description of oxides, concretions, nodules, groundmass and granular microfabrics, voids, clay coatings, and bioturbation.

3.4 Determination of clay mineralology

The mineralogy of clays associated with paleosols within the Dinosaur Park

Formation were semi-quantitatively analysed using the JEOL JXA 8200 electron microprobe housed at the University of Calgary Laboratory for Electron Microbeam

Analysis (Figure 3.1). Four thin sections from four separate stratigraphic sections containing macroscopic pedogenic features were used. The cover slips were removed and the thin sections polished for these examples. Thin sections were then coated with a 22 nm layer of carbon using a high-vacuum carbon evaporator. Both compositional and

topographical (secondary electron and backscatter electron) images were obtained for

analysis.

Figure 3.1. Photograph of JEOL JXA-8200 Electron Microprobe used in this thesis. Credit: UCLEMA, Department of Geoscience, University of Calgary. Additionally, energy dispersive spectrometer (EDS) analyses were used to semi- quantitatively determine the composition of clays within the samples.

3.5 Geochemical analysis

Pedotypes and illuvial paleosols exhibiting distinct B horizons (see Table 3.1) were sampled at a 20-cm interval in the field in order to produce geochemical profiles of each. Material selected for geochemical analysis is representative of each horizon and relatively unoxidized. A total of 115 samples were prepared and analyzed by X-ray

fluorescence spectrometry (XRF) conducted by SGS Minerals Services in Calgary,

Alberta and reported in terms of element weight percent or ppm (Appendix B).

Preparation of each sample involved crushing to 75% passing 2 mm and pulverizing to

85% passing 75 µm. Ninety-six samples were analyzed through XRF for detection of major oxide and trace element concentrations. An additional nineteen samples were analyzed for detection of major oxide concentrations only.

Since original parent material composition was not determined (see Driese et al.

2005), molecular weathering ratios are used as proxies of pedogenic processes (see

Feakes and Retallack 1988, Jones 1982, Retallack 1997a). Oxide weight percents are

normalized to their molecular weight (see Feakes and Retallack 1988, Jones 1982,

Retallack 1997a) and inserted into the following molecular ratios as proxies of pedogenic processes: lessivage (clayeness; ); calcification ( ); base loss

( ); hydrolysis ( ); salinization ( ); and leaching ( ). Each of these pedogenic proxies are reported for each pedotype in Figures 5.1a, 5.2, 5.3, 5.4, 5.5,

5.6, and 5.7.

Increased chemical weathering (hydrolysis) in soils is due to increased temperature and precipitation (Sheldon et al. 2002). Depletion of alkali and alkaline elements (Ca, Mg, Na, K) is accelerated in the presence of water and warmth at the expense of refractory elements such as aluminum (Al). This correlation in modern soils is

used to estimate of mean annual precipitation (MAP) and mean annual temperature

(MAT) in paleosols. MAT and MAP is calculated using all the samples taken from all Bt

or Bw horizons encountered in the various sections by inserting the oxide weight

percentages of Bt and Bw horizons into the chemical index of alteration minus potash

(CIA-K) calculations of Sheldon et al. (2002) in the following manner:

These data are averaged for each profile and reported in Appendix C.

3.6 Pedotypes

Paleosols that exhibit similar pedogenic features are assembled into pedotypes using the approach of Retallack (1994). The application of modern soil taxonomy to paleosols is contested because of a reliance on typological designations to infer environmental conditions (see Dahms 1998, Dahms and Holliday 1998, Fastovsky and

McSweeney 1987, Mack et al. 1993). The possibility of “extinct” soil types that are no longer expressed also limits any application of US soil taxonomy to paleosols (Fastovsky and McSweeney 1987). Nevertheless, the creation of pedotypes (sensu Retallack 1983) that are unassigned to modern taxonomic groups helps to constrain interpretations of general soil development and drainage provided that inferences regarding

41 paleoenvironments and paleoclimates are based solely on the pedogenic features present in the paleosols rather than the similarity of the paleosols to modern soil types.

Chapter Four: Features of Dinosaur Park Formation paleosols

4.1 Colour of paleosols

The colour of a paleosol horizon is a consequence of parent material (the

concentration of iron and manganese compounds in the matrix; Schwertmann 1993,

Torrent et al. 1980), geomorphic setting, and hydrology (Richardson and Daniels 1993) and can be diagnostic of paleoenvironmental conditions (Retallack 1997a). Dinosaur Park

Formation paleosols vary in colour from dark green to light green and lime green, light gray to brownish gray and light brown. The redox state of iron oxides present in soils colours most aerobic soils (Schwertmann 1993). However, hydrologic conditions affect reduction conditions and the accumulation of iron precipitates which colour soils

(Richardson and Daniels 1993). Bright soil colours occur in well-drained areas and change to dull gray colours in depressions (Richardson and Daniels 1993). Where gleyed soils form due to a high water table, the reducing state is created by organic decay in the ground water and causes extensive reduction of the soil matrix (Wright et al. 2000).

4.1.1 Groundwater and surface water gley

Low-chroma (gley) colours are a common feature of clayey soils on which stagnant water ponds annually. The light colour is produced by anaerobic microbes that reduce brown and red iron oxides and hydroxides from the ferric state to the ferrous, drab-coloured state (Retallack 1997a, Retallack 2001b). Where soils are saturated by a high watertable, gley soils can be also produced by the reduction of organic mater that then causes extensive reduction of the soil matrix (Wright et al. 2000). After groundwater levels lower, oxidation can occur along exposed ped surfaces resulting in ferric iron accumulations near the surface (Wright et al. 2000). Groundwater gleying is an indication

of iron depletion and water saturation in sediments for less than 50% of an annual flooding cycle (Daniels et al. 1971).

Surface water gley (pseudo-gley and pseudo-gley mottling) typically occurs in soils containing an impervious layer and are not typically saturated with water (Buurman

1980). If rainwater stagnates in the soil because of the impervious layer, iron becomes reduced similar to gleying created by groundwater fluctuations (Duchaufour 1982,

PiPujol and Buurman 1997, PiPujol and Duurman 1994). Larger pores that extend through the impervious layer are locally reduced leaving the rest of the matrix oxidized

(Buurman 1980). The matrix of these soils is divided by the impermeable layer: the matrix exposed to stagnant water is bleached and mottled whereas the matrix below is typically coloured (Buurman 1980, PiPujol and Duurman 1994). Modern soils that express pseudo-gley are observed in places such as Bangladesh and the monsoon region of Indonesia where seasonal inundation of soils by floodwaters causes extensive surface ponding (Datta and Subramanian 1997, PiPujol and Buurman 1998, Tan 2008).

4.2 Bioturbation

Most paleosols of the Dinosaur Park Formation contain root traces (Figure 4.1).

Root traces are horizontally and vertically oriented throughout the profiles and many are coalified. Although specific root morphology was not documented, the positioning of the root traces in a paleosol profile was noted. These data can be useful in ascertaining the general maturity of a floral community hosted in a paleosol. Some root traces that occur in upper horizons are intermittently filled with sandy material. Microscopically, root traces appear as dark linear features due to opaque organic debris (Figure 4.1). Burrows are less common in thin section, generally vertical, and

Figure 4.1. Photomicrograph of sample BB30-12 under normal light. Dark, linear features are root traces within pores filled with opaque organic debris. filled with clay. In thin section, burrows appear as small (≤ 1 cm) crescent striated b- fabrics.

4.3 Microstructure and Fabric of Groundmass

Paleosols in the Dinosaur Park Formation preserve microstructures and groundmass fabrics. Microstructures include peds: natural aggregates of soil that form between roots, burrows, cracks, or other planes of weakness by the alternating dry and wet conditions that respectively shrink and swell clays (Retallack 2001b). Particular environments create characteristic ped morphologies that are recognized in paleosols

(Retallack 1997a). Macroscopic peds are virtually absent from Dinosaur Park Formation paleosols, however, in thin section, rare peds are observed as polyhedral and subangular structures 5-10 mm across with irregular boundaries. Groundmass fabrics are also

45 preserved in paleosols in the form of birefringence fabrics (b-fabrics) and are characterized by the presence of arranged equidimensional speckles of optically oriented clay that produce birefringence in cross-polarized light (Bullock et al. 1985, Retallack

1997a). The most common b-fabrics recognized in Dinosaur Park Formation paleosols are granostriations (see Figure 4.2a and 4.2b), where clays are laminated against grains; porostriation, where clays occur as hypocoatings on pores (Figure 4.3a and 4.3b); stipple- speckled, consisting of individual isolated speckles; and mosaic-speckled, where the birefringent speckles are in contact with each other (Bullock et al. 1985). Stipple- speckled and mosaic-speckled b-fabrics form during early pedogenesis whereas undifferentiated or poorly developed b-fabrics characterize very weakly developed soil horizons (Bullock et al. 1985). Monostriated fabrics appear in thin section as individual birefringent streaks in the groundmass whereas reticulate striated fabrics occur as two or more sets of birefringent streaks intersecting at right angles (Bullock et al. 1985).

Crescent striated fabrics are elongated, worm-like features with a crescent (bow) shaped internal fabric (Bullock et al. 1985).

4.4 Clay accumulations

Clay accumulations are a common, conspicuous illuvial feature of Dinosaur Park

Formation paleosols. They appear as thin (0.01-0.1 mm), laminated coatings on clastic grains, roots, pores, and voids. The presence of clay accumulations in Dinosaur Park

Formation paleosols provides evidence for illuvial translocation of clay (Bullock and

Thompson 1985). When precipitation is sufficiently higher than evapotranspiration, clay is carried down from surficial horizons and, provided the soil desiccates periodically, retained (McKeague 1983, Retallack 2001b). Many paleosols in the Dinosaur Park

Formation reveal down-profile changes in geochemical proxies of clayeness, base loss, and hydrolysis suggesting clay illuviation was a significant pedogenic process (Bown and

Kraus 1981, Driese et al. 2005, Feakes and Retallack 1988). The frequency of illuvial features also indicates substantial periods of precipitation during pedogenesis (Retallack

2001b).

Figure 4.2a. Photomicrograph of sample BB30-15 in normal light.

Figure 4.2b. Same as Figure 4.2a but in polarized light. Birefringent clays surround centre clast forming granostriated b-fabric in the terminology of Bullock et al. (1985).

Figure 4.3a. Photomicrograph of sample BB30-14 showing root traces under normal light.

Figure 4.3b. Same as Figure 4.1a but under polarized light. The external margins of the root traces contain birefringent clays or porostriated b-fabrics in the terminology of Bullock et al. (1985).

4.5 Slickensides

Only two paleosols in the measured sections of the Dinosaur Park Formation contain slickensides. They are found in dark gray (2.5Y 5/2 & 5Y 6/2) organic rich horizons and are characteristic of Vertisols (Clayey soils with high shrink-swell potential;

Retallack 2001b). In thin section, slickensides appear as planes of strongly striated b- fabric from the alignment of birefringent clays. They occur in smectite-rich horizons, where seasonal wetting and drying causes ped heave and shearing within soils (Retallack

2001b).

4.6 Ferruginous pedofeatures

Ferruginous void, pore, and grain hypocoatings occur internally and externally as very thin (> 1 mm), dark opaque features in thin section (Figures 4.4a & b). When

49 ferrous-rich water encounters oxidizing and/or higher pH conditions, iron and manganese precipitates and coats grains, peds, carbonate nodules, and root traces. Although iron coatings around grains occur, no well-developed mottling is observed in Dinosaur Park

Formation paleosols indicating iron illuviation was not a significant pedogenic process

(Schwertmann 1993); perhaps this is due to the composition of parent material. Small

(0.5-1.5 mm) iron nodules also occur and appear in thin section as subrounded to well- rounded opaque concentrations (Figures 4.4a). Mottles, or irregularly shaped glaebules with diffuse boundaries, are expressed microscopically within the Dinosaur Park

Formation and are typically related to ferruginous depletion or saturation.

4.7 Siderite

Siderite is a farroan or Fe2+-rich carbonate (Moore et al. 1992) and is observed as

nodules and layers in Dinosaur Park Formation paleosols and pedogenically unmodified

deposits (see Figure 4.5). Sideritized horizons in paleosols are organic rich with common

root traces and typically contain few other conspicuous pedogenic features. Authogenic

siderite commonly forms in organic rich wetland soils and its presence suggests that

anoxic (reducing) conditions developed rapidly during the history of the sediment

(Landuydt 1990, Moore et al. 1992, Wright et al. 2000). Additionally, siderite pebbles

and gravels occur in the coarser, channelized deposits within Dinosaur Park Formation

(Eberth 2005) which suggests some siderites have a diagenetic origin (Wright et al.

2000).

4.8 Coal

Lignitic and sub-bituminous coals occur in the upper ~15 m of the Dinosaur Park

Formation in the tidally influenced shoreline deposits of the Lethbridge Coal Zone

(Eberth 2005). The maximum number of coal beds in any given vertical succession is four and each is typically less than one meter thick (Eberth 1996). The presence of these lignites suggests oxygen-depleted or reducing conditions (Wright et al. 2000) and the co- occurrence of fine laminae in the Lethbridge Coal Zone also suggest bottom waters were at least temporarily anoxic.

Figure 4.5a. Photomicrograph ferruginous external hypocoating around an iron rich nodule (N).

Figure 4.4b. Photomicrograph of external ferruginous hypocoating of root trace in direct light. Iron oxide has also precipitated within pore space.

Figure 4.5. Photograph of Bat Section (#4 on Figure 1.1) within the lower Dinosaur Park Formation. Arrows indicate location siderite horizons. Pick is 1.3m for scale.

Chapter Five: Dinosaur Park Formation pedotypes

Seven pedotypes and two non-pedogenically modified deposits are recognized within the sediments of the Dinosaur Park Formation (Figure 5.1a). Paleosols are weakly to well developed, range in thickness from 14 to 364 cm thick (AVG = 138.2 cm, σ =

90.2, Table 5.1), and represent 72% of all measured overbank deposits recorded in the

Formation (n=41). Dinosaur Park Formation paleosols are hosted in drab-coloured claystones, mudstones, siltstones, sandy siltstones, and silty sandstones. Most distinct paleosol profiles are separated by decimetre-to-metre thick sandstones (see Figure 5.1a).

The various pedofeatures and degrees of development exhibited by these paleosols indicate that a variety of landscape positions are preserved in the sediments of the

Dinosaur Park Formation. The stratigraphic location of each paleosol is illustrated in

Figure 5.1a and described in Section 5.9.

5.1 Category 1 pedotype

Only three Category 1 paleosols are recorded in the Dinosaur Park Formation and are present exclusively within the Gravel Pit Section. Category 1 paleosols range in thickness from 112 to 279 cm thick (AVG = 207.3 cm, σ = 85.9; Figure 5.1b). Distinct lithologic units in Category 1 paleosols can be separated by undulatory contacts (see

Figure 5.1b). This pedotype contains common dispersed organic matter, common horizontal and vertical root traces (some coalified; Figure 5.1c), weakly-developed slickensides, and weakly-developed clay coatings. Redoximorphic features including concretions (Figure 5.1d), external iron hypocoatings, and weak ferruginous impregnation of the groundmass can be seen microscopically.

Figure 5.1a. Measured sections of the Dinosaur Park Formation. Numbers following section names correspond to Figure 1.1. See text for discussion.

Depth (cm) Horizon Lithology Munsell colour (UCL Redoximorphic features B‐fabric Carbonates/ Notes colour) siderite Category 1 paleosols (location of pedotype: 6.96 metres in Gravel Pit section) 163 Bw Mudstone 5Y 6/2 (Drab yellow) Groundmass weakly impregnated Predominantly moasic‐speckled None Clay coatings are macroscopic but weakly with areas of stipple‐speckled, developed, lower contact is undulatory monostriated, and reticulated b‐ fabrics 29 Bss Silty 5Y 4/2 (Grayish olive) Groundmass impregnated; Fe Stipple‐speckled None Matrix colour oxidizes brown, silckensides are mudstone concretions macroscopic but weakly developed

87 C Sandy 7.5Y 6/2 (Deep greenish Groundmass weakly Stipple‐speckled None Several root traces are coalified, and are generally siltstone yellow impregnated; Fe concretions thick (~1.5 cm wide)

Category 2 paleosols (location of pedotype: 15.20 metres in Bat section) 15 A Mudstone 10YR 4/2 (Grayish Weak impregnation of the Stipple‐speckled Occasional Groundmass fabrics are obscured by dispersed yellowish brown groundmass with Fe concretions siderite organic matter and debris nodules and pebbles 310 Bw Siltstone 7.5Y 6/2 (Deep greenish Weak impregnation of the Stipple‐speckled None yellow) groundmass with Fe concretions

Category 3 paleosols (location of pedotype: 3.98 metres in Bat section) 65 A Silty 10YR 4/2 (Grayish Groundmass is very weakly Stipple‐speckled Siderite Some of groundmass obscured by organic matter mudstone yellowish brown impregnated with Fe and contain nodules and Fe concretions pebbles

41 Bw Silty 5Y 5/2 (Greenish Groundmass is very weakly Stipple‐speckled None Granostriation is very weakly developed, mudstone yellow) impregnated with Fe and contain occasional but poorly develped slickensides Fe concretions

114 Bt Siltstone 5Y 6/2 (Drab yellow) Groundmass weakly impregnated Stipple‐speckled None Porostriation is well‐developed, granostriation is with Fe and Fe concretions occur weakly developed

Category 4 paleosols (location of pedotype: 57.87 metres in Iddesleigh section) 86 Abtss Mud/clayston 2.5Y 5/2 (Light olive Groundmass is unimpregnated Moasic‐speckled with occasional Diffuse e brown) with Fe but Fe concretions occur reticulated b‐fabrics siderite nodules 55

81 Bw Silty 5Y 6/2 (Drab yellow) Groundmass is unimpregnated Moasic‐speckled None mudstone with Fe but Fe concretions occur

27 C Interlaminate mud: 2.5Y Groundmass is unimpregnated Moasic‐speckled with local stipple‐ None d mudstone 4/2(Moderate olive with Fe but Fe concretions occur speckled and siltstone brown) silt:5Y 7/2(Grayish yellow)

Category 5 paleosols (location of pedotype: 8.92 metres in Risk Section) 40 Ag Siltstone 10Y 8/1 Groundmass is unimpregnated Mosaic‐speckled to locally stipple‐ None speckled 23 1Btg Siltstone 5Y 6/2 (Drab yellow) Groundmass is predominantly Moasic‐speckled None unimpregnated with Fe but in thin section, concentrations of Fe occur in crevasses

46 2Btg Siltstone 5Y 6/1 Groundmass is weakly Moasic‐speckled None impregnated with Fe and contains Fe concretions 35 C Siltstone with 5Y 5/2 (Light yellowish Groundmass is weakly Stipple‐speckled None Some of the groundmass is obscured by organic fine clay olive brown) impregnated with regions of matter lamina heavy Fe impregnation Category 6 paleosols (location of pedotype: 4.97 metres in Bone Bed 30 section) 10 A Mudstone 2.5Y 5/2 (Light olive Weakly developed ferruginous Moasic‐speckled with occasional None Abundant dispersed organic matter brown) impregnation of the groundmass reticulated b‐fabrics

24 Bt Mudstone 5Y 7/2 (Grayish yellow) Weakly developed ferruginous Weakly moasic‐speckled None Numerous and large clay lined crevasses occur impregnation of the groundmass

60 1Bg Mudstone 10Y 6/1 (Deep greenish Groundmass is unimpregnated Predominantly moasic‐speckled None yellow) with Fe; Fe mottle occur in thin with occasional monostriated and section reticulated regions 22 2Bg Silty 10Y 7/2 (Moderate Groundmass is unimpregnated Stipple‐speckled with minor areas None Crescent‐striated b‐fabrics; numerous clay lined mudstone greenish yellow) with Fe of moasic‐speckled crevasses occur in thin section

Category 7 paleosols (location of pedotype: lowermost Gravel Pit section) 174 Bt Siltstone 10Y 7/2 (Moderate Groundmass uniformly and Moasic‐speckled w/ occasional None Well‐developed porostriation, granostriation is greenish yellow) weakly impregnated with Fe reticulate fabrics moderatly developed. Occasional coal fragments. concretions 80 1Bwg Siltstone 10Y 6/1 (Deep greenish Groundmass locally impregnated Moasic‐speckled None yellow) surrounding Fe concretions 40 E Sandy 10Y 8/1 Groundmass locally and weakly Stipple‐speckled None Occasional porostriation, weak granostriation siltstone to impregnated with Fe concretions sandstone 34 2Btg siltstone 10Y 7/2 (Moderate None Well‐developed clay coatings greenish yellow)

Table 5-1. Pedotypes and their pedofeatures. See text for discussion.

Figure 5.1b. Stratigraphic profile of Category 1 paleosol. These paleosols contain dispersed organic matter, root traces, slickensides, and clay coatings. The various molecular weathering ratios reveal that the pedogenic horizons are poorly- differentiated. See Sect ion 5.1 for further description. See Figure 5.1a for key.

Figure 5.1c. Hand sample from Bss horizon of Category 1 pedotype containing coalified root trace.

Figure 5.1d. Photomicrograph of iron concretions within groundmass of Category 1 pedotype under normal and direct light. Ferruginous impregnation of the groundmass occurs adjacent to some concretions (A).

Clay coatings surrounding grains are poorly to moderately developed (granostriation;

Figure 5.1e). Clay coatings along fissures or root walls (porostriation; Figure 5.1f) only

occur in the uppermost horizon. Lower horizons exhibit stipple-speckled b-fabrics whereas the b-fabric of the uppermost horizon is generally stipple-speckled with local areas of mosaic-speckled and striated b-fabrics.

Molecular weathering ratios of Category 1 paleosols (Figure 5.1b) reveal limited geochemical differentiation between the horizons within the paleosol profile. However, molecular weathering ratios of clayeness and base loss significantly decrease within the lowermost silty mudstone horizon whereas hydrolysis markedly increases. Clayeness and oxidation decrease down profile but increase in the lowermost mudstone horizon and drop off within the lowermost sandstone horizon. Leaching is variable within the horizons but is relatively low and similar to Category 5 paleosols indicating that chemical elements have mostly remained within the profile.

5.1.1 Interpretation

Category 1 paleosols are interpreted as weakly-developed paleosols situated on poorly to moderately-drained habitats in which the watertable fluctuated during the year.

Limited geochemical differentiation of the various horizons, relatively low values of leaching, and absence of well-developed pedofeatures all suggest that the subaerial exposure of Category 1 paleosols was limited. The presence of redoximorphic features and slickensides indicates that the paleosol profile experienced alternating wet and dry conditions and possibly fluctuations of the watertable. Although the absence of well- developed clay coatings might suggest minimal precipitation, the limited subaerial

Figure 5.1e. Photomicrograph of grainostriation in Category 1 pedotype: birefringent clay tightly surrounding monocrystalline quartz grain (Q) under polarized light.

Figure 5.1f. Photomicrograph of porostriation in Category 1 pedotype: birefringent clays along interior wall of pore (P) under polarized light.

exposure of the Category 1 paleosol may have been insufficient to develop macroscopic illuvial features under significant precipitation. Well-developed clay coatings can require thousands of years to develop (Fedoroff et al. 1990, McKeague 1983, Retallack 1997a,

Retallack 2001b). The relatively low weathering ratio of leaching indicates that Category

1 paleosols were generally less well-drained than other Dinosaur Park Formation paleosols.

5.2 Category 2 pedotype

Category 2 paleosols range in thickness from 15 to 325 cm (AVG = 125.8 cm, σ =

92.4 cm; Figures 5.1 and 5.2, Table 5.1). These paleosols developed on silty mudstones sharply overlain by mudstones. Category 2 paleosols are the most common paleosol type in the Dinosaur Park Formation and represent 25% of all measured overbank deposits in the Formation (n=14). These paleosols contain abundant organic matter (Figure 5.2a) but root traces are rare. Organic rich horizons grade laterally into discontinuous siderite ledges.

Dispersed organic matter is ubiquitous at a microscopic scale. Ferruginous impregnation of Category 2 paleosols is moderate. Clay coatings around clasts

(granostriation; Figure 5.2b) and long fissures or root walls (porostriation; Figure 5.2b) are observed in thin section but are only weakly-developed. Small iron concretions (≤

0.5mm) are rare. Where visible, the b-fabric of Category 2 paleosols is stipple-speckled

(Figure 5.2c).

Molecular weathering ratios of clayeness and calcareousness are relatively consistent through the profile (Figure 5.2). Indices of hydrolysis slightly decrease down profile. Molecular weather ratios of base loss and leaching increase down profile and are higher than those of Category 1 paleosols indicating more intense weathering of the parent material and greater removal of soluble ions during pedogenesis (Figure 5.2).

5.2.1 Interpretation

Category 2 paleosols are interpreted as weakly-developed paleosols that formed proximally to active channels on a moderately-drained floodplain. The presence of microscopic clay coatings suggests that the Category 2 paleosols must have developed on habitats that experienced free drainage for parts of the year. Although gley-colours are absent from these paleosols, the presence of microscopic iron concretions and moderate ferruginous impregnation of the groundmass reveal these paleosols were subject to fluctuations of the watertable. Additionally, the lack of gleyed-colours in these paleosols suggests that the siderite layers preserved in Category 2 paleosol are a post burial alteration of the uppermost organic rich horizons. The absence of well-developed illuvial pedofeatures in these paleosols may be unrelated to drainage or amount of precipitation but rather to the immature nature of these Category 2 paleosols. Inceptisols (incipient soils) do not display the features characteristic of the prevailing environment and/or climate because many pedofeatures (such as significant illuvial clay accumulations) require hundreds to thousands of years to form (Fedoroff et al. 1990, McKeague 1983,

Porter et al. 1998, Retallack 1997a, Retallack 2001b). Weakly-developed pedofeatures, limited horizon differentiation, and common stacking pattern (see Figure 5.2 and Table

5.1) of these paleosols suggests limited time of soil formation due to frequent flooding.

Therefore, Category 2 paleosols most likely formed proximal to active channels.

Figure 5.2. Stratigraphic profile of Category 2 paleosol. These paleosols contain dispersed organic matter and root traces. The various molecular weathering ratios reveal that the pedogenic horizons are generally poorly-differentiated. See Section 5.2 for further description. See Figure 5.1a for key.

Figure 5.2a. Hand sample of Bw horizon within Category 2 pedotype showing dispersed organic matter and root traces.

Figure 5.2b. Photomicrograph of Category 2 paleosol under polarized light. Weakly developed grainostriation around monocrystalline quartz grain (G) and weakly developed porostriation along pore wall (P) are both present.

5.3 Category 3 pedotype

Category 3 paleosols range in thickness from 95 to 280 cm (AVG = 170.8 cm, σ =

68.2 cm; Figures 5.1 and 5.3; Table 5.1) and represent 18% of all measured overbank deposits in the Dinosaur Park Formation (n=10). These paleosols are developed on sharply bounded intervals of siltstones overlain by silty mudstones (Figure 5.3). Category

3 paleosols contain abundant root traces (Figure 5.3a), abundant dispersed organic matter

(Figure 5.3a), common clay coatings, rare and weakly-developed slickensides, and rare siderite nodules.

All horizons in Category 3 paleosols contain moderate ferruginous impregnation of the groundmass at a microscopic scale (Figure 5.3b). Mottles (Figure 5.3b) and small iron concretions (~ 0.2 mm; Figure 5.3b) with rare external iron hypocoatings are present in Category 3 paleosols. The uppermost horizon is strongly impregnated with amorphous organic debris. Where visible, the b-fabric of all horizons is stipple-speckled. Clay coatings along fissures or root walls (porostriation) are present in the lowermost horizon.

Clay coatings around clasts (granostriation) are present throughout the profile but are more weakly developed than Category 2 paleosols.

Molecular weathering ratios of Category 3 paleosols reveal better differentiation between the various horizons than observed in previous Dinosaur Park Formation pedotypes. Clayeness decreases down profile concomitantly with an increase in grain size. Apart from a pronounced positive deviation within the lower 10 cm of the uppermost horizon, the indices of oxidation and calcareousness remain low and invariable. As in Category 2, 4 and 6 paleosols, the leaching index is moderate and

increases with depth until the lowermost horizon, indicating chemical constituents produced by parent material weathering are substantially leached from the profile.

5.3.1 Interpretation

Category 3 paleosols are interpreted as moderately-developed paleosols that formed in moderately-drained areas of the floodplain that experienced fluctuations of the watertable. Clay coatings observed in Category 3 paleosols formed due to downward migration of clay and indicate Category 3 paleosols experienced periods of substantial precipitation (McKeague 1983). Although ferruginous impregnation of the groundmass and leaching indices indicate oxidizing conditions, the presence of microscopic mottles indicates that fluctuations of the watertable intermittently impeded drainage in these paleosols.

Category 3 paleosols are similar in colour and horizon arrangement to the less well-developed Category 2 paleosols. Within the lower Bat section (Figure 5.1a) stacked

Category 3 paleosols appear to be less developed in terms of horizon differentiation and pedofeatures and vertically “grade” into Category 2 paleosols while maintaining their distinctive colour. Accordingly, Category 3 paleosols may be more well-developed versions of Category 2 paleosols that experienced greater pedogenic modification due to a longer time of soil formation but represent very similar drainage conditions. Therefore,

Category 2 paleosols developed in habitats that experienced more frequent flooding and burial relative to Category 3 paleosols.

Figure 5.3. Stratigraphic profile of Category 3 paleosol. These paleosols contain dispersed organic matter, root traces, clay coatings, weakly developed slickensides, and rare siderite nodules. The various molecular weathering ratios reveal that the pedogenic horizons are generally better developed than previous pedotypes. See Section 5.3 for further description. See Figure 5.1a for key.

Figure 5.3a. Hand sample from Bt horizon within Category 3 pedotype containing root traces and dispersed organic matter.

Figure 5.3b. Photomicrograph of Category 3 pedotype containing small iron concretions (C) and locally strong ferruginous impregnation of the groundmass (M) under direct light.

5.4 Category 4 pedotype

Category 4 paleosols range in thickness from 79 to 277 cm (AVG = 177.6 cm, σ =

70.7 cm; Figures 5.1 and 5.4; Table 5.1). These paleosols represent 9% of all measured overbank deposits in the Dinosaur Park Formation (n=5). Category 4 paleosols display fining upward intervals consisting of finely interlaminated mudstone and siltstone, silty mudstones, and claystones (Figure 5.4). These paleosols contain rare root traces (some coalified; Figure 5.4a), common dispersed organic matter (Figure 5.4a), common clay coatings (Figure 5.4b), and rare slickensides. The lowermost horizon is composed of parallel-laminated, heterolithic strata (finely interlaminated mudstone and siltstone

“pinstripe” sediment). The lower boundary of Category 4 paleosols is conformable with underlying strata and can be laterally continuous for tens of metres before pinching out

(up to 130 metres).

Weak ferruginous impregnation of the groundmass occurs at a microscopic scale

(Figure 5.4c). Small (~0.5 mm) iron concretions (Figure 5.4c), mottles (Figure 5.4d) and ferruginous accumulations within fissures and root walls (Figure 5.4d) are present throughout Category 4 paleosol horizons. The b-fabric of the lowermost horizon is stipple-speckled (Figure 5.4e) whereas overlying silty mudstone and mudstone horizons are mosaic-speckled to uniform (Figure 5.4f). Clay coatings around grains

(granostriation) and clay coatings along small crevasses (porostriation) are also present.

Molecular weathering ratios reveal limited horizon differentiation within the profile. Indices of clayeness, oxidation, calcareousness, and base loss remain relatively constant with depth and decrease only within the lower horizons. Molecular weathering ratios of base loss and leaching are moderate, similar to Category 2, 3, and 6 paleosols

72 indicating that parent material weathering was more protracted and leaching of chemical continuants out of the profile was more intense than other paleosol categories.

5.4.1 Interpretation

Category 4 paleosols are interpreted as moderately-developed paleosols that formed on moderately-drained paralic and/or mudflat deposits subject to alternating wet and dry conditions. The presence of clay coatings reveals these paleosols were relatively well-drained and experienced periods of substantial precipitation (McKeague 1983).

Moderate values of leaching and base loss also indicate that these paleosols were relatively well-drained, allowing for leaching of chemical elements released during parent material weathering. The presence of slickensides suggests these paleosols also experienced alternating wet and dry conditions. The occurrence of common illuvial features in association with limited horizon development inferred from molecular weathering ratios indicates that Category 4 paleosols are moderately-developed.

Previous sedimentological investigations of the Dinosaur Park Formation describe the heterolithic “pinstripe” deposits that compose the lowermost horizon in Category 4 paleosols as paralic crevasse splay and/or mudflat deposits (Eberth 1996, Eberth et al.

1990, Koster and Currie 1987). Category 4 paleosols likely developed on these paralic environments.

Figure 5.4. Stratigraphic profile of Category 4 paleosol. These paleosols contain dispersed organic matter, root traces, clay coatings, and rare slickensides. The various molecular weathering ratios reveal that the pedogenic horizons are generally well- developed.

Figure 5.4a. Hand sample of Bt horizon within Category 4 pedotype showing dispersed organic matter and root traces.

Figure 5.4b. Hand sample of Bt horizon within Category 4 pedotype showing extensive clay coatings. Organic debris and coalified plant material are included within the clay.

Figure 5.4c. Photomicrograph of Category 4 paleosol showing iron concretions (C) and ferruginous impregnation of the groundmass under normal and direct light.

A M

Figure 5.4d. Photomicrograph of iron accumulations (A) within fissure and iron mottles (M) within Category 4 pedotype under normal and direct light.

Figure 5.4e. Photomicrograph of groundmass of lower Bt horizon within Category 4 pedotype showing stipple-speckled b-fabric.

Figure 5.4f. Photomicrograph of groundmass of upper Bw horizon within Category 4 pedotype showing mosaic-speckled to uniform b-fabric.

5.5 Category 5 pedotype

Category 5 paleosols range in thickness from 90 to 144 cm (AVG = 117, σ = 38.2;

Figures 5.1 and 5.5; Table 5.1). These paleosols represent 4% of the all measured overbank deposits in the Dinosaur Park Formation (n=2). Category 5 paleosols consist of fining upward gleyed siltstones frequently capped by organic rich horizons that intermittently form siderite ledges (Figure 5.1a and Table 5.1). Category 5 paleosols contain common to rare dispersed organic matter (Figure 5.5a), abundant clay coatings

(Figure 5.5b), few root traces, and rare burrows. Category 5 paleosol also contain very- fine clay laminae that are penetrated by root traces.

Microscopically, ferruginous impregnation of the groundmass is strong throughout the profile but especially in lower horizons within Category 5 paleosols

(Figure 5.5c). Redoximorphic features (mottles and iron concretions; Figure 5.5d) are common within Category 5 paleosols. Abundant organic debris obscures the groundmass of upper horizons (Figure 5.5e). Where clearly visible, b-fabrics are stipple-speckled to mosaic-speckled (Figure 5.5e) with abundant clay coatings around clasts (granostriation) and along fissures or root walls (porostriation) within the uppermost horizon.

Variations and trends within molecular weathering ratios of Category 5 paleosols indicate more pronounced horizon differentiation than seen in previous Dinosaur Park

Formation pedotypes (Figure 5.5). Trends in clayeness, calcareousness, and oxidation generally increase down profile. Indices of base loss and leaching are the lowest of all

Dinosaur Park Formation paleosols and decrease down profile indicating weathering of

Figure 5.5. Stratigraphic profile of Category 5 paleosol. These paleosols are variously gleyed and contain dispersed organic matter, root traces, clay coatings, and rare burrows. Despite gleying, the various molecular weathering ratios reveal that the pedogenic horizons are generally well-developed. See Section 5.5 for further description. See Figure 5.1a for key.

Figure 5.5a. Hand sample of Category 5 pedotype containing dispersed organic debris.

Figure 5.5b. Hand sample of Category 5 pedotype containing clay coatings (clay skins; C).

Figure 5.5c. Photomicrograph of 2Btg horizon within the Category 5 pedotype showing strong ferruginous impregnation of the groundmass under normal and direct light.

O M M

Figure 5.5d. Photomicrograph of 1Btg horizon within the Category 5 pedotype showing iron concretions (C), mottles (M), and organic debris (O) under normal and direct light.

Figure 5.5d. Photomicrograph of groundmass of upper Ag horizon showing abundance of organic matter and stipple-speckled b-fabric under polarized light. the parent material and leaching of chemical elements was low but more intense in the upper horizons (Figure 5.5).

5.5.1 Interpretation

Category 5 paleosols are interpreted as moderately-developed paleosols developed on habitats subject to fluctuations of the watertable. Although well-developed pedofeatures occur in Category 5 paleosols, the presence of fine sedimentary features and moderate geochemical differentiation within the various horizons indicates these paleosols were only moderately-developed. The low indices of base loss and leaching corroborate the suggestion that these paleosols experienced limited weathering of the parent material and leaching of chemical elements out of the profile. The gleyed matrix of nearly every Category 5 paleosol horizon implies these paleosols experienced extended periods of water saturation (generally three to six months a year) due to a high

82 watertable (Daniels et al. 1971). However, the presence of abundant clay coatings and common redoximorphic features provides evidence for substantial precipitation and fluctuations of the watertable. The development of abundant clay coatings requires at least seasonal percolation of meteoric water in an unsaturated soil for thousands of years

(Fedoroff et al. 1990, McKeague 1983, Retallack 2001b). The presence of gleyed horizons and illuvial features suggests Category 5 paleosols initially developed with a high watertable that later became better drained through time allowing for the creation of well-developed illuvial features.

5.6 Category 6 pedotype

Category 6 paleosols range in thickness from 62 to 244 cm (AVG = 144.6 cm, σ =

92.13 cm; Figures 5.1 and 5.6; Table 5.1). These paleosols are relatively rare, representing 5% of all measured overbank deposits in the Dinosaur Park Formation

(n=3). These fining upward paleosols include abundant dispersed organic matter, abundant root traces (some coalified and clay lined; Figure 5.6a), abundant clay coatings

(Figure 5.6a), and common coalified plant material. Category 6 paleosols are distinctive in that well-developed illuvial features occur in horizons above gleyed horizons (Figure

5.5). The lateral extent of Category 6 paleosols makes them a pervasive feature of the lowermost Dinosaur Park Formation throughout the “core area” of Dinosaur Provincial

Park (see Figure 5.6b).

Microscopically, ferruginous impregnation of the groundmass is weakly- developed in all Category 6 paleosol horizons (Figure 5.6c). The groundmass of the uppermost horizon is also impregnated with amorphous organic debris. Iron concretions are rare and are present predominantly in the upper horizons (Figure 5.6; Table 5.1).

Where visible, the b-fabric is predominantly mosaic-speckled (Figure 5.6d). Clay coatings around clasts (granostriation) and along fissures or root walls (porostriation) also occur.

Molecular weathering ratios of Category 6 paleosols reveal significant differentiation of the various horizons (Figure 5.6). Trends in clayeness and calcareousness decrease with depth in the profile. Indices of base loss and leaching are moderate, similar to Category 2, 3, and 4 paleosols, and decrease with depth indicating

Figure 5.6. Stratigraphic profile of Category 6 paleosol. These fining upward paleosols contain dispersed organic matter, root traces, clay coatings, and coalified plant material. The various molecular weathering ratios reveal that the pedogenic horizons are generally well-developed and similar to Category 4 paleosols. See Section 5.6 for further description. See Figure 5.1a for key.

O R

Figure 5.6a. Hand sample from Bt horizon of Category 6 pedotype showing coalified organic debris (O), clay coatings (C), and root traces (R).

Figure 5.6b. Exposures of lowermost Dinosaur Park Formation within “core” area of Dinosaur Provincial Park. Dinosaur Park-Oldman formational contact is just below vegetated surface. Two stacked Category 6 paleosols (within brackets) are present as extensive layers throughout the lowermost Dinosaur Park Formation. Staff (circled) is 1.5m.

Figure 5.6c. Photomicrograph of 1Bg horizon within the Category 6 pedotype showing weak ferruginous impregnation of the groundmass under normal and direct light. Mottles (M) are rare in Category 6 paleosols but can be well developed.

1 2

Figure 5.6d. Photomicrograph of groundmass of 2Bg horizon within the Category 6 pedotype under polarized light. 2) Same as 1 but rotated 50° clockwise showing mosaic-speckled b-fabric.

that the chemical constituents produced by the weathering of the parental material were at least partially drained out of the profile.

5.6.1 Interpretation

Category 6 paleosols are interpreted as moderately- to well-developed paleosols situated in moderately-drained areas of the floodplain. The presence of well-developed pedofeatures and geochemically well-differentiated horizons indicate significant soil development. The occurrence of well-developed illuvial features and mottles in upper horizons and paucity of pedofeatures in the lower, gleyed horizons suggests upper horizons experienced moderate-drainage and fluctuations of the watertable whereas lower horizons experienced impeded drainage for more than 25% of the year (Daniels et al.

1971). Moreover, trends in base loss and leaching imply that the upper horizons of

Category 6 paleosols were not only better drained relative to lower horizons but also experienced greater leaching of chemical constituents released during weathering. The creation of well-developed clay coatings within the upper horizons of Category 6 paleosols implies these paleosols received abundant precipitation (McKeague 1983).

5.7 Category 7 pedotype

Category 7 paleosols range in thickness from 135 to 328 cm (AVG = 195.5 cm, σ

= 89.4 cm; Figures 5.1 and 5.7; Table 5.1). These paleosols represent 7% of all measured overbank deposits in the Dinosaur Park Formation (n=4). Category 7 paleosols contain abundant dispersed organic matter (Figure 5.7a), abundant root traces (Figure 5.7a), abundant clay coatings (Figure 5.7a), rare coalified plant debris (Figure 5.7a), and rare

88 burrows. The Category 7 pedotype is developed on a 9-metre wide (measured oblique to paleoflow direction), silty lenticular channel-fill deposit. Category 7 paleosols are readily identifiable by the presence of a porous, light yellow sandy siltstone horizon that frequently under- and overlies horizons that contain abundant clay coatings. This sandy siltstone horizon contains macroscopic clay coatings. Additionally, half of all measured

Category 7 paleosols including the Category 7 pedotype exhibit lower horizons with gleyed matrices (n=2).

Microscopically, ferruginous impregnation of the groundmass is weakly- developed to absent (Figure 5.7b). Mottles (Figure 5.7b) and iron concretions are present but rare throughout these paleosols. B-fabrics are stipple-speckled in the coarser-grained sandy siltstone horizon and mosaic-speckled in the finer-grained siltstone horizons. Clay coatings along fissures or root walls (porostriation; Figure 5.7c) occur in the sandy siltstone horizon whereas clay coatings surrounding grains (granostriation) occur more prominently in siltstone horizons (Figure 5.7d).

Molecular weathering ratios reveal the various horizons of Category 7 paleosols are moderately-differentiated (Figure 5.7). Indices of clayeness and calcareousness decrease down profile whereas hydrolysis increases with depth. Indices of base loss and leaching also increase with depth and are the highest of any Dinosaur Park Formation paleosol indicating intense weathering of parent material and leaching of chemical elements out of the profile.

Figure 5.7. Stratigraphic profile of Category 7 paleosol. These paleosols contain dispersed organic matter, root traces, clay coatings, rare coalified plant material, and rare burrows. The various molecular weathering ratios reveal that the pedogenic horizons are moderately developed. See Section 5.7 for further description. See Figure 5.1a for key. . 89

R P

Figure 5.7a. Hand sample of upper Bt horizon within the Category 7 pedotype containing dispersed organic debris (O), coalified plant material (P), and a large root trace (R) containing clay coatings(C).

Figure 5.7b. Photomicrograph of Bt horizon within the Category 7 pedotype showing the near lack of ferruginous impregnation of the groundmass under normal and direct light. Mottles (M) are rare but do occur within Category 7 paleosols.

Figure 5.7c. Photomicrograph of Bt horizon within the Category 7 pedotype showing porostriation (P) around a fissure under polarized light.

Figure 5.7d. Photomicrograph of Bt horizon within the Category 7 pedotype showing grainostriation around a monocrystalline quartz grain (Q) under polarized light.

5.7.1 Interpretation

Category 7 paleosols are interpreted as well-developed paleosols formed preferentially on coarse, well-drained, channel-fills. The horizons and pedofeatures of

Category 7 paleosols contain pedofeatures and horizons that are very similar to albic paleosols found in the uppermost Oldman Formation (see Matson et al. 2008). The discrepancy in colour between the two similar paleosol types is likely a product of the different source materials between the Oldman and Dinosaur Park formations (see

Chapter 2). The presence of well-developed pedofeatures, moderately-differentiated geochemical profiles, and greater values of base loss and leaching than any other pedotype in the Dinosaur Park Formation indicate Category 7 paleosols are well- developed. In Category 7 paleosols, the greater porosity of the channel-fill facilitated the intense leaching of chemical elements produced by weathering of the parent material and produced an albic (E) horizon (Figure 5.7, Table 5.1). The presence of very well- developed illuvial features in the uppermost and lowermost horizons indicate that

Category 7 paleosols were situated on landscapes that were relatively stable for thousands of years and experienced periods of substantial precipitation (Birkeland 1999, McKeague

1983, Retallack 1997a). The presence of common redoximorphic features demonstrates that Category 7 paleosols were subject to fluctuations of the watertable. Furthermore, the presence of gleyed horizons with well-developed illuvial pedofeatures in some Category

7 paleosols reveals that the watertable remained high for significant parts of the year

(Daniels et al. 1971), or that a high watertable impeded drainage during initial pedogenesis of these channel-fills and improved through time.

5.8 Non-pedogenically modified deposits

5.8.1 Category A deposits

Category A deposits consist of massive or finely-laminated siltstone and mudstone deposits or both, ranging in thickness from 14 to 364 cm (AVG = 82 cm, σ=

97.09). Category A deposits represent 20% of all measured overbank deposits (n=11).

These non-pedogenically modified deposits are organic rich and contain siderite nodules.

5.8.1.1 Interpretation

Category A deposits represent various floodplain/overbank deposits that were exposed for short periods of time, if at all. The lack of pedogenic features (e.g. root traces, clay coatings) suggest the subaerial exposure of these facies was insufficient for plants to colonize these deposits before burial. Many pedogenically unmodified deposits contain high levels of organic material regardless of their proximity to vegetation (Boggs

2001).

5.8.2 Category B deposits

Category B deposits represent 7% of all measured overbank deposits (n=4). These heterolithic “pinstripe” deposits consist of finely-laminated siltstones and mudstones that range in thickness from 27 to 237 cm (AVG =110.25, σ = 90.34). These deposits contain dispersed organic matter, coal fragments, and siderite nodules and/or layers. Category B deposits were recorded exclusively in the Iddesleigh Section east of Dinosaur Provincial

Park (see Figure 1.1).

5.8.2.1 Interpretation

Category B deposits are documented in the Dinosaur Park Formation and interpreted as paralic crevasse-splay and/or mudflat deposits that endured no pedogenic modification (Eberth 1996, Eberth et al. 1990, Koster and Currie 1987). The lack of pedogenic features also suggests that these deposits were not subaerially exposed for enough time for plants to colonize the sediment before burial. Although sampling methods do not allow statistical comparisons to be made, the infrequency of Category A and B deposits within the measured sections compared to pedogenically modified deposits suggests plant colonization was rapid on the Dinosaur Park Formation floodplain.

5.9 Location of paleosols within Dinosaur Park Formation

Category 1 paleosols occur in the stratigraphic interval between 10 metres above the Oldman-Dinosaur Park formational contact and 54 metres above the contact in the middle of the Dinosaur Park Formation (see Figure 5.1a; Table 5.1). Category 2 paleosols occur approximately 15 metres above the Oldman-Dinosaur Park formational contact and continue into the middle portion of the Dinosaur Park Formation. Category 3 paleosols occur approximately four metres above the Oldman-Dinosaur Park formational contact and continue into the middle of the Dinosaur Park Formation (see Figure 5.1a). Category

4 paleosols occur in the upper 57 metres of the Dinosaur Park Formation and within the

Lethbridge Coal Zone (see Figure 5.1a). Category 5 paleosols only occur approximately nine metres above the Oldman-Dinosaur Park formational contact in limited areas (see

Figure 5.1a). Although only recorded in Section 3 (Bat Section), Category 6 paleosols

occur extensively five metres above the Oldman-Dinosaur Park formational contact (see

Figure 5.1a) in the Park (See Figure 1.1). Category 7 paleosols occur at or just above the

Oldman-Dinosaur Park formational contact (see Figure 5.1a).

Chapter Six: Paleoenvironmental reconstruction of the Dinosaur Park Formation

Three distinct paleolandscapes are interpreted from the Dinosaur Park Formation using pedofeatures of the paleosols and their stratigraphic distribution (Figure 6.1). These paleolandscapes are recorded within the lowermost seven metres of the Dinosaur Park

Formation, the next 47 metres, and the upper 26 metres including the Lethbridge Coal

Zone (see Section 5.9). The variation of pedofeatures within the various paleosols indicate better drained paleosols developed in areas topographically higher or more distal to channels or both and poorly-drained paleosols developed in areas topographically lower or more proximal to channels or both (Kraus 1997, Wright et al. 2000).

The paleolandscapes of the Dinosaur Park Formation identified here are generally composed of better-drained “dryland” habitats regularly exposed to oxidizing conditions and less well-drained “wetland” habitats in areas with a high watertable or where the water table fluctuated and at times the surface where ponds or oxbow lakes formed. Dry land regions of the floodplain are characterized by periods of impeded drainage, although hydrologic conditions varied throughout the year. These are generally topographically high areas and/or more distal areas in relation to active channels. Wetland regions are characterized by impeded drainage and are topographically low in relation to the channel levee (alluvial ridge).

6.1 Lowermost Dinosaur Park Formation paleolandscape

The paleoenvironments of the lowermost seven metres of the Dinosaur Park

Formation (see Figure 5.1a and Figure 6.1) are generally less diverse than the overlying paleoenvironments in the Formation and consist primarily of dryland habitats. These

include pedogenically modified channel-fills (Category 7 paleosols) that experienced impeded drainage in the lower horizons. The advanced maturity and lack of compound

Category 7 paleosols suggests these paleosols occupied areas more distal to active channels. However, the channel-fill lithology that characterizes Category 7 paleosols could occupy any position on the floodplain. Habitats situated topographically lower and/or more proximal to active channels still experienced relatively free drainage but were subject to frequent flooding and sediment input (proximal dry floodplains; Category

2 paleosols). In more distal reaches of the floodplain, more mature paleosols with free drainage formed due to less frequent floods and sediment input (distal dry floodplains;

Category 3 paleosols). Although these paleosols are characterized by free drainage, the watertable still fluctuated and suggests that dryland habitats were not always topographically higher than more proximal habitats.

6.2 Middle Dinosaur Park Formation paleolandscape

The middle Dinosaur Park Formation (7 to 54 metres; see Figure 5.1a and Figure

6.1) section displays the most diverse paleolandscape assemblage observed in the

Formation. Wetland habitats consist of pedogenically unmodified fine-grained floodplain sediments (overbank deposits; Category A deposits), pond habitats with no pedogenic modification (stagnant water; Category B deposits), and habitats adjacent to ponds with newly-colonized shores (immature wetlands; Category 1 paleosols).

Better-drained habitats of the middle Dinosaur Park Formation consist of habitats topographically lower and/or more proximal to active channels that experienced relatively free drainage but were subject to frequent flooding and sediment input

(proximal dry floodplains; Category 2 and 5 paleosols). Category 5 paleosols occur in habitats with drainage conditions that improved overtime. This may be due to the natural migration of active channels away from these habitats or the aggradation of floodplain sediment. In more distal reaches of the floodplain, more mature paleosols with free drainage formed due to less frequent floods and sediment input (distal dry floodplains;

Category 3 and 6 paleosols). Just as in the Lower Dinosaur Park Formation, these paleosols exhibit evidence of watertable fluctuation suggesting these landscapes, although situated more distal to active channels, were topographically similar to proximal habitats (Category 2 and 5 paleosols).

6.3 Upper Dinosaur Park Formation paleolandscape

The paleoenvironments of the upper Dinosaur Park Formation (54 to 65 metres;

Figure 5.1a and Figure 6.1) consist predominantly of wetland habitats consisting of pedogenically unmodified overbank deposits (Category A deposits) situated proximal to active channels and poorly-drained, pedogenically unmodified lacustrine habitats

(stagnant water; Category B deposits). Better-drained habitats were situated distal to active channels and received less frequent sediment input facilitating the development of more mature paleosols with free drainage (distal dry floodplains; Category 4 and 6 paleosols). The presence of abundant coal fragments and layers (Lethbridge Coal Zone in uppermost Dinosaur Park Formation), shallow roots and a small number of burrows suggests that these wetlands were host to lush and abundant soil organisms. These wetlands eventually deposited the coal layers (Lethbridge Coal Zone) that mark the top of the Dinosaur Park Formation. The transgression of the Bear Paw Sea resulted in several

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pulses of marine water that inundated the paralic environments of the Dinosaur Park

Formation creating mud filled valleys.

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Figure 6.1. Illustration of climofunctions, paleoenvironments, and faunal turnovers in stratigraphic context of the Dinosaur Park Formation. MAP (1,2, and 3) climofunctions have no scale and are only presented as relatively “wetter” or “dryer” against the mean of each (thick dashed line; see Chapter 6 for discussion). Thin dashed line indicates approximate positions of Ryan and Evans’s (2005) faunal zones (see section 2.3.2 for discussion).

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Chapter Seven: Summary and prospectus

Dinosaur Park Formation paleolandscapes consist of generally well-drained habitats that experienced frequent overbank flooding and ponding. Specifically, these paleolandscapes are composed of well-drained distal dry floodplains, better-drained and topographically higher proximal dry floodplains, seasonal wetlands, and poorly-drained pond deposits. These habitats are consistent with the well-drained floodplain interpretation of Noad (1993), Eberth and Hamblin (1993), and Wood (1989). However, numerous paleosols exhibiting low chroma and gleyed horizons implies hydromorphy became an increasingly significant process in Dinosaur Park Formation habitats up- section where paleolandscapes become relatively stable.

Well-drained paleoenvironments do not remain consistent throughout the deposition of the Dinosaur Park Formation. Beginning with well-drained habitats in the lowermost Dinosaur Park Formation, paleolandscapes transition into seasonal wetland/dry floodplain mosaic habitats at seven metres above the Oldman-Dinosaur Park formational contact and prevail for a majority of the Formation’s deposition (Figure 6.1).

The uppermost Dinosaur Park Formation including the Lethbridge Coal Zone preserves a lowered diversity of habitats as tidal influence and the formation of coals become a more significant process in landscape genesis.

The distribution of fossil taxa is also inconsistent throughout the strata of the

Dinosaur Park Formation. However, the two faunal turnovers hypothesized by Ryan and

Evans (2005) that separate ornithischian taxa into three distinct faunal zones do not coincide with paleolandscape changes as inferred in this thesis (Figure 6.1). The lower

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“Centrosaurus-Corythosaurus” zone contains all of the Lower paleoenvironment and nearly half of the Middle paleoenvironment (see Chapter 6 and Figure 6.1). Additionally, the “Styracosaurus-Lambeosaurus” zone contains the upper half of the Middle paleoenvironment and a majority of the Upper paleoenvironment. The Upper paleoenvironment and the “Pachyrhinosaurid-L. magnicristatus-C. irvinensis” zone correspond the best of the three zones and may be due to the significant landscape modification experienced during the transgression of the Bearpaw Seaway. Nevertheless, the incongruence between the Lower and Middle paleoenvironments and the lower two faunal zones of Ryan and Evans (2005) suggests that the transition between generally better-drained habitats low in the Formation to generally less-well drained habitats did not significantly alter the composition of ornithischian taxa. At present, the paleolandscapes of the Dinosaur Park Formation and the changes through time they undergo do not appear to significantly correlate with the turnovers observed in ornithischican fauna (sensu Ryan and Evans, 2005).

In contrast, macroflora data collected from the Dinosaur Park Formation is consistent with the paleoenvironmental interpretations provided by paleosols. The presence of numerous plant fossil taxa, such as horsetails, ginkgos, ferns, and tree ferns, that today live in warm climates suggest a seasonal warm-temperate climate with little or no frost (Braman 2005, Russell 1989). Climofunction data recorded Dinosaur Park

Formation paleosols containing accumulation horizons (B horizons) reiterates macrofloral and palynological data suggesting warm-temperate, subhumid climates with no frost. Tree ring data (Koppelhus 2005a) suggests that Dinosaur Park Formation

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habitats experienced seasonality. The presence of vertic pedofeatures contained within two Dinosaur Park Formation pedotypes also suggests habitats experienced some degree of seasonality where periods of significant precipitation (over 1,000 mm/year) were followed by extensive desiccation.

Palynological, macrofloral, sedimentological, and now paleopedological study all indicate Dinosaur Provincial Park paleoenvironments experience warm-temperate to subhumid conditions with periods of significant precipitation during the Late Cretaceous.

However, the presence of caliches within coeval deposits of Montana (Two Medicine

Formation) and southernmost Alberta (Oldman Formation) imply a more arid paleoenvironment existed contemporaneously (Horner and Currie 1996, Jerzykiewicz and

Sweet 1988, Trexler 2001, Troke 1993). A paleoenvironmental gradient existed across the region during the Late Cretaceous. A denizen of the Late Cretaceous would have experienced progressively wetter and perhaps less seasonal conditions traveling north from what is now Montana until reaching the future location of Dinosaur Provincial Park.

This gradient may very well have influenced taphonomic disparities, differences in microfossil assemblages, and in small part, paleobiogeographical patterns within ornithischian dinosaurs across the western interior of North America.

The paleolandscape of southern Alberta during the deposition of the Dinosaur

Park Formation would not be so alien to modern humans. A flat, shallow descending floodplain dissected by wide meandering rivers lined with intensely vegetated zones and the occasional discarded oxbow lake. Areas further away from active channels are dryer and display more mature but less dense vegetation. Today, this scene can be found in the

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humid south-eastern coast of the United States, the tropical wet lowlands of Colombia, and the seasonal wetland habitats of Bangladesh.

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Porter, D. A., T. McCahon, and M. D. Ransom. 1998. Differentiating pedogenic and diagenetic properties in a Cretaceous paleosols in Kansas. Quaternary International 51/52:35. Rahmani, R. A., and J. F. Lerbekmo. 1975. Heavy-mineral analysis of Upper Cretaceous and Paleocene sandstone in Alberta and adjacent areas of Saskatchewan. Pp. 607- 632. In M. Caldwell, W., ed. The Cretaceous System in the Western Interior of North America Geological Association of Canada, Special Paper 13. Retallack, G. J. 1983. A paleopedological approch to the interpretation of terrestrial sedimentary rocks: The mid-Tertiary fossil soils of Badlands National Park, South Dakota. Geological Society of America Bulletin 94:823-840. Retallack, G. J. 1988a. Down-to-Earth Approaches to Vertebrate Paleontology. Palaios 3:335-344. Retallack, G. J. 1988b. Field Recognition of Paleosols. Pp. 1-20. In J. Reinhardt, and W. R. Sigleo, eds. Paleosols and Weathering Through Geologic Time: Principles and Applications. Geological Society of America. Retallack, G. J. 1994. A pedotype approach to latest Cretaceous and earliest Tertiary paleosols in eastern Montana. Geological Society of America Bulletin 106:1377- 1397. Retallack, G. J. 1997a. A colour guide to paleosols. John Wiley & Sons Ltd. . Retallack, G. J. 1997b. Dinosaurs and Dirt. Pp. 345-360. In D. L. Wolberg, E. Stump, and G. Rosenberg, eds. Dinofest The Academy of Natural Sciences, Arizona State University. Retallack, G. J. 2001a. Paleosols. Pp. 296-300. In E. Geller, ed. McGraw-Hill yearbook of science and techonology. McGraw-Hill, New York. Retallack, G. J. 2001b. Soils of the past: an introduction to paleopedology. Unwin Hyman, Inc. Richardson, J. L., and R. B. Daniels. 1993. Stratigraphic and Hydraulic Influences on Soil Color Development. . Pp. 109-126. In R. J. Luxmoore, J. M. Bigham, and E. J. Ciolkosz, eds. Soil Color: proceddings of a symposium sponsored by Division S-5 and S-9 of the Soil Science Society of America Soil Science Society of America, San Antonia, Texas. Russell, D. A. 1970. Tyrannosaurs from the Late Cretaceous of western Canada. National Museum National Science Publications in Palaeontology 1:1-34. Russell, D. A. 1977. A vanished world, the dinosaurs of western Canada. National Museums of Canada, Ottawa. Russell, D. A. 1989. An Odyssey in Time: The Dinosaurs of North America University of Toronto Press, Toronto. Ryan, M. J., and D. C. Evans. 2005a. Late Cretaceous ceratopsids from the Judith River Group, Alberta, and the recognition of Dinosaurian faunal zones within Dinosaur Provincial Park. Pp. 92-93. In D. R. Braman, F. Therrien, E. B. Koppelhus, and W. Taylor, eds. Dinosaur Park Symposium. Royal Tyrrell Museum of Palaeontology Drumheller, Alberta.

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APPENDIX A: DINOSAUR PROVINCIAL PARK SECTIONS

Gravel Pit Section

Sample GP-02

Light gray sandy siltstone with rare dispersed organic matter, rare root traces, and clay

coatings. Grains are well-sorted, very fine grained (2.5 Φ), blocky, anhedral, and

subrounded. Sample is composed of approximately 20% sand (10% monocrystalline

quartz). Groundmass is locally impregnated with Fe around Fe concretions that are typically <0.3mm across. B-fabric is stipple speckled with occasional porostriation

around roots. Granostriation is weakly developed.

Sample GP-03

Brownish gray siltstone with dispersed organic matter and abundant root traces.

Chalcedony <1% Organic debris is common throughout slide. Groundmass is locally

impregnated with iron around Fe concretions. B-fabric is mosaic-speckled.

Sample GP-08

Light green siltstone with occasional coals, rare dispersed organic matter, rare root traces,

and clay filled burrows. Grains are very well sorted, very fine-grained (3.5-4.0 Φ),

anhedral, blocky, and subrounded. Uniformly and weakly impregnated with Fe

concretions are < 0.4mm in diameter. B-fabric is mosaic-speckled with occasional

reticulate-speckled. Granostriation is moderately developed. Porostriation is very well

developed.

Sample GP-34

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Light green to gray sandy siltstone fining upwards into a siltstone with root traces, with some coalified root traces. Grains are very well-sorted, very fine-grained (3.0 Φ), anhedral, blocky, and subrounded. Sample is composed of approximately 40% sand.

Groundmass is locally impregnated where Fe concretions produce diffuse Fe halos. B- fabric is stipple-speckled. Granostriation may occur, but is poorly developed.

Sample GP-35

Very dark greenish brown silty mudstone with abundant dispersed organic matter and occasional root traces, minor slickensides, and coalified root traces. Grains are moderately well-sorted, very fine-grained (3.5 Φ), blocky to platy, anhedral, and subangular. Sample is composed of approximately 10% sand. Organic debris partially obscures ground mass and b-fabric. Groundmass appears unimpregnated. Fe concretions occur and are generally < 0.2mm in diameter. B-fabric is uniformly stipple-speckled with major zones of porostriation. Granostriation also occurs and is moderately developed.

Organic debris is very common in sample and obscures groundmass and b-fabric in some places.

Sample GP-41

Green mudstone with occasional dispersed organic matter with horizontal and vertical root traces, and possible clay coatings. Grains are well-sorted, very fine-grained (3.0 Φ), anhedral, blocky to platy, and subangular to subrounded. Sample is composed of approximately 10% sand (5% monocrystalline quartz, 2% polycrystalline quartz, 2% K- spar, and less than 1% of chlorite, lithic fragments and chert), 5% organic debris, 5% opaques, and 80% silt and mud. Groundmass is unimpregnated, however, Fe mottles do

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occur (are typically less than 0.3mm) and Fe concretions occur (and are less than

0.4mm). B-fabric is mosaic-speckled to stipple-speckled with occasional monostriated and reticulated b-fabrics. Poorly organized clay accumulations also occur, as well as birefregent zones of clay accumulations that may have been bioturbated. Granostriation is poorly developed to absent.

Risk Section

Sample R-30

Light green (stained brown) siltstone with fine clay lamina and root traces. Grains are

very well sorted, very fine-grained (2.5-3.0 Φ), blocky, anhedral, and subangular to subrounded. Sample is composed of approximately 40% sand (30% monocrystalline quartz, 5% k-spar, 2% polycrystalline quartz, 2% chlorite, and less than 1% of hornblende, chert, Carlsbad, mica, and chert), 5% organic debris, 5% opaques, and 50% silt and clay. Groundmass is not uniform. Predominantly, groundmass is weakly impregnated while localized regions are heavily impregnated with Fe. This localized Fe concentration may be diagenetic. B-fabric is uniformly stipple-speckled. However, some of the groundmass and b-fabric is obscured by the abundance of organic matter.

Sample R-32

Light green siltstone with root traces and clay coatings. Grains are very well sorted, very fine-grained (3.5 Φ), anhderal, cubic to platy and blocky, and subrounded. Sample is composed of approximately 20% sand (10% monocrystalline quartz, 5% polycrystalline quartz, 3% k-spar, 1% chlorite, and less than 1% of hornblende, zeolite, zircon, orthoclase, and lithic fragments), 5% opaques, 5% organic debris, and 70% silt and clay.

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Goundmass is weakly impregnated with Fe. Fe concretions occur and are generally <

0.2mm in diameter. B-fabric is predominantly mosaic-speckled with localized regions of uniformity. Sedimentary features can be partially seen in thin section. Large (0.4mm) lithic fragments with chert and chalcedony occur in sample. Side opposite the label has a grain size difference.

Sample R-34

Greenish gray siltstone with clay coatings, clay filled burrows, and partially iron stained.

Grains are not uniform in slide. Predominantly, grains are very well sorted, very fine- grained (2.5 Φ), blocky, andhedral, and subrounded to subangular. Sample is composed of approximately 40% sand (20% monocrystalline quartz, 10% polycrystalline quartz, 5% k-spar, 2% chlorite, 1% lithic fragments, and less than 1% chert, chalcedony, and hornblende), 5% organic debris, 5% opaques, and 50% silt and clay. Groundmass is predominantly unimpregnated, however, localized regions where crevasses have formed concentrate Fe. Fe concretions also occur and are typically < 0.2 mm in diameter. B- fabric is mosaic-speckled with some regions of poorly organized clay accumulations.

Some clay accumulations appear to be disturbed clays that once lined a tube or root, however, this is difficult to illustrate. Granostriation is weakly developed.

Sample R-35

Light Green siltstone with dispersed organic matter and occasional root traces. Grains are very well sorted, very fine-grained (2.5-3.0 Φ), blocky, andhedral, and subangular to subrounded. Sample is composed of approximately 30% sand (15% monocrystalline quartz, 10% k-spar, 3% polycrystalline quartz, 1% chert, and less than 1% hornblende,

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chlorite, and zircon), 5% opaques, 3% organic debris, and 62% silt and clay. Groundmass is unimpregnated. However, clouds of undifferentiated clay occur throughout slide. B- fabric is mosaic-speckled to locally stipple-speckled with areas or brefrigent organized clays and is likely the product of porostriation. Granostriation also occurs throughout slide.

Centrosaur Section

Sample CS-03

Olive green siltstone with root traces (some coalified), clay coatings (some around root traces), and possibly minor slickensides. Grains are well sorted, very fine-grained (3.0

Φ), anhedral, blocky, and subrounded. Sample is composed of approximately 30% sand

(20% monocrystalline quartz, 5% polycrystalline quartz, 3% k-spar, 1% chert, and less than 1% hornblende, chlorite), 2% opaques, and 3% organic debris, and 65% silt and clay. The abundance of organic matter obscures the groundmass and pedogenic features.

Groundmass appears unimpregnated. B-fabric, where visible, is stipple-speckled to mosaic-speckled in localized areas. Large (0.4mm across) regions of clay accumulations.

Granostriation occurs but is weakly developed.

Sample CS-05

Light gray sandy siltstone with root traces and minor clay coatings. Grains are well sorted, very fine-grained (3.0 Φ), anhedral, blocky, and subrounded to rounded. Sample is composed of approximately 30% sand (20% monocrystalline quartz, 5% polycrystalline quartz, 3% k-spar, 1% zircon and less than 1% chlorite, hornblende, and chert), 2% opaques, 5% organic debris, 63% silt and clay. Groundmass is unimpregnated except

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where Fe nodules are locally staining surrounding groundmass. B-fabric is stipple- speckled. Regions of poorly organized organic debris obscures view of underlying groundmass.

Sample CS-06

Grains are very well sorted, very fine-grained (2.5 Φ), blocky, anhedral and subangular to subrounded. Sample is composed of approximately 40% sand (35% monocrystalline quartz, 2% polycrystalline quartz, 1% lithic fragments and less than 1% of hornblende, k- spar, zircon, orthoclase), 10% opaques, 10% organic debris, and 40% silt and clay.

Groundmass is unimpregnated and Fe concretions are < 0.2mm. B-fabric is stipple- speckled to locally mosaic-speckled. Granostriation occurs but is weak. Organic debris occurs as root traces in section. Few other pedogenic features present.

BAT SECTION

Sample BS-12

Light greenish gray siltstone with dispersed organic matter, occasional root traces. Grains

are very well sorted, very fine-grained (3.0 Φ), subrounded, anhedral, and platy. Sample

is composed of approximately 30% sand (20% monocrystalline quartz, 4%

polycrystalline quartz, 4% k-spar, 1% chert, and less than 1% of hornblende, chlorite,

mica, lithic fragments, and opal), 3% opaques, 2% organic debris, and 65% silt and clay.

Groundmass is uniformly but weakly impregnated with Fe. Fe concretions occur and are

< 0.2 mm in diameter. B-fabric is uniform to stipple-speckled. One large region (7mm

along the long axis) is composed of birefregent clay aligned as porostriation. Occurs as a

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clay lined tube as was seen in handsample before thin sectioning. Granostriation is present but weakly developed.

Sample BS-14

Dark green silty mudstone with rare root traces. Grains are very well sorted, very fine- grained (2.5-3.0 Φ), subrounded, anhedral, and blocky. Sample is composed of approximately 10% sand (5% monocrystalline quartz (with many inclusions), 3% polycrystalline quartz, 1% k-spar, and less than 1% chert, hornblende, chlorite, opal, spenel, zircon, and lithic fragments), 5% organic debris, 3% opaques, and 82% silt and clay. Groundmass is weakly impregnated surrounding Fe concretions which are generally

< 0.2mm in diameter. B-fabric is stipple-speckled with weakly developed granostriations.

Sample BS-17

Chocolate milk silty mudstone that is organic rich, with green clay interclasts. Grains are moderately-poorly sorted, very fine to fine-grained (2.0-3.0 Φ), subrounded to subangular, blocky, and anhedral to ovoid. Sample is composed of approximately 30% sand (20% polycrystalline quartz, 5% lithic fragments, 3% monocrystalline quartz (with vacuoles), 1% k-spar, and less than 1% hornblende, chlorite), 3% opaques, and 20% organic debris, and 47% silt and clay. Groundmass is uniform and very weakly impregnated with Fe. Fe concretions occur and are generally < 0.2mm across. B-fabric is mostly obscured. Where observable, b-fabric is stipple-speckled. Organic matter is so pervasive in sample, most pedogenic features and groundmass are obscured.

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IDDESLEIGH SECTION

Sample IS-90

Green mudstone interlaminated with light gray siltstone. Grains are very well sorted, very

fine grained (2.5 Φ), subangular, blocky, and anhedral. Sample is composed of

approximately 50% sand (25% monocrystalline quartz, 15% k-spar, 5% polycrystalline

quartz, 3% chert, 1% chlorite, and less than 1% of hornblende, opal, zeolite, and zircon),

5% opaques, 5% organic debris, and 40% silt and clay. Groundmass is unimpregnated with Fe. Fe concretions are generally <0.2mm. B-fabric is predominantly mosaic-

speckled localized regions of stipple-speckled. Crevasses in the sample are formed where

monostriated to mass accumulated clay occurs as a linear feature. These likely

accumulated by clay migration in a tube or root trace.

Sample IS-92

Greenish brown silty mudstone with clay and silty regions and root traces (some

coalified). Grains are well sorted, very fine-grained (3.0-3.5 Φ), subrounded to

subangular, blocky, and anhedral. Sample is composed of approximately 10% sand (6%

monocrystalline quartz (many with vacuoles), 2% k-spar, 1% polycrystalline quartz, and

less than 1% of chert, chlorite, hornblende, zircon), 15% organic debris, 2% opaques, and

73% silt and clay. Groundmass is unimpregnated with Fe. Fe concretions occur in

sample and are < 0.1mm in diameter. B-fabric is mosaic-speckled with weakly developed

granostriation. Organic debris occurs in roots that appear to be in situ in slide.

Porostriation also occurs in sample; the largest is 3.0 mm long.

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Sample IS-95

Dark gray green, organic rich mud/clay stone with clay coatings, slickensides and root traces. Grains are well sorted, very fine-grained (3.0 Φ), subrounded, anhedral, and blocky. Sample is composed of approximately 10% sand (5% polycrystalline quartz, 3% monocrystalline quartz, 1% k-spar, and less than 1% chert, hornblende, chlorite, and zircon), 2% opaques, 10% organic debris, and 78% silt and clay. Groundmass is unimpregnated with Fe. Most Fe concretions are less than 0.1mm in diameter; largest is

0.5mm long along the long axis. B-fabric is mosaic-speckled with some reticulated- striated and minor granostriation.

BONEBED 30 SECTION

Sample BB30-10

Lime-green silt to silty mudstone with root traces and clay lined root traces. Grains are

well sorted, very fine-grained (3.0 Φ), subrounded, anhedral, and blocky. Sample is

composed of approximately 10% sand (9% monocrystalline quartz, and less than 1% of polycrystalline quarts, chert, chlorite, and k-spar, olivine?), 10% organic debris, 5%

opaques. Groundmass is unimpregnated with iron. Opaques consist predominantly of Fe

concretions. B-fabric is stipple-speckled with localized and minor mosaic-speckled where organic debris has prevented tearing of grains during sectioning. Crescent-striated fabrics occur in slide and are evidence of abundant bioturbation. Numerous clay lined crevasses also occur and are typically less than .2mm in length. Granostriation occurs but is weakly developed.

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Sample BB30-12

Greenish gray mudstone with dispersed organic matter and root traces, numerous and well developed clay coatings and coalified plant material. Grains are moderately well sorted, very fine-grained (2.5-3.5 Φ), subrounded, anhedral, and blocky. Although courser regions occur in slide, sample is composed of approximately 10% sand (5% monocrystalline quartz (typically with multiple inclusions), 4% polycrystalline quartz, and less than 1% of k-spar, lithic fragments, chert), 5% organic debris, 3% opaques, and

83% silt and clay. Groundmass is uninpregnated with Fe. Fe mottles occur in slide and are typically .2mm across. B-fabric is predominantly mosaic-speckled with occasional monostriated and/or reticulated striated regions. Organic matter is common throughout slide and seem to maintain dendrite root morphology.

Sample BB30-14

Lime green mudstone with root traces, dispersed organic matter, and clay coatings.

Grains are very well sorted, very fine-grained (3.5-4.0 Φ), unable to determine morphology of predominant grain size class. Sample is composed of approximately 2% sand (monocrystalline quartz?), 15% opaques (cannot differentiate organics from Fe concretions), and 82% silt and clay. Groundmass is unimpregnated with Fe. B-fabric is undifferentiated to weakly mosaic-speckled. Organic debris is somewhat confined as outlines were roots are located. Crevasses in the sample occur where large (visible to naked eye) accumulations of clay occur. These clay accumulations occur as generally ovoid or elongate shapes and very large (3mm across). Perhaps this indicates neighboring accumulations are part of a single tube that was sectioned in such a way as to produce the

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distinct morphology. Whatever the case, it’s a great indicator of massive migration of clays within the soil profile.

Sample BB30-15

Light brown mudstone with abundant dispersed organic matter (A horizon?). Grains are moderately sorted, fine to very fine-grained (2.5-3.0 Φ) subrounded, anhedral, and blocky. Sample is composed of approximately 10% sand (8% monocrystalline quartz, 1% polycrystalline quartz, and less than 1% of hornblende, k-spar, chert, mica, and lithic fragments), 2% opaques, 15% organic debris, and 63% silt and clay. Groundmass is weakly or unimpregnated with Fe. B-fabric is mosaic-speckled with occasionally developed reticulated striation and well developed granostriation. Organic debris is so common that slide appears “stained” as an Fe impregnation.

APPENDIX B: MOLECULAR WEATHERING RATIOS

APPENDIX C: CLIMOFUNCTIONS